Creating A Guon

Difficulty: 3/10

First, you need to make a new file called: AdvancedPlayerOrbitalItem that inherits from PassiveItem, then drop this in there

private void CreateOrbital(PlayerController owner)
        {
            GameObject targetOrbitalPrefab = (!(this.OrbitalPrefab != null)) ? this.OrbitalFollowerPrefab.gameObject : this.OrbitalPrefab.gameObject;
            bool flag = this.HasUpgradeSynergy && this.m_synergyUpgradeActive;
            if (flag)
            {
                targetOrbitalPrefab = ((!(this.UpgradeOrbitalPrefab != null)) ? this.UpgradeOrbitalFollowerPrefab.gameObject : this.UpgradeOrbitalPrefab.gameObject);
            }
            bool flag2 = this.HasAdvancedUpgradeSynergy && this.m_advancedSynergyUpgradeActive;
            if (flag2)
            {
                targetOrbitalPrefab = ((!(this.AdvancedUpgradeOrbitalPrefab != null)) ? this.AdvancedUpgradeOrbitalFollowerPrefab.gameObject : this.AdvancedUpgradeOrbitalPrefab.gameObject);
            }
            this.m_extantOrbital = PlayerOrbitalItem.CreateOrbital(owner, targetOrbitalPrefab, this.OrbitalFollowerPrefab != null, null);
            bool flag3 = this.BreaksUponContact && this.m_extantOrbital;
            if (flag3)
            {
                SpeculativeRigidbody component = this.m_extantOrbital.GetComponent<SpeculativeRigidbody>();
                bool flag4 = component;
                if (flag4)
                {
                    SpeculativeRigidbody speculativeRigidbody = component;
                    speculativeRigidbody.OnRigidbodyCollision = (SpeculativeRigidbody.OnRigidbodyCollisionDelegate)Delegate.Combine(speculativeRigidbody.OnRigidbodyCollision, new SpeculativeRigidbody.OnRigidbodyCollisionDelegate(this.HandleBreakOnCollision));
                }
            }
            bool flag5 = this.BreaksUponOwnerDamage && owner;
            if (flag5)
            {
                owner.OnReceivedDamage += this.HandleBreakOnOwnerDamage;
            }
            this.OnOrbitalCreated(this.m_extantOrbital);
        }

        // Token: 0x060000F6 RID: 246 RVA: 0x0000B5A8 File Offset: 0x000097A8
        public static GameObject CreateOrbital(PlayerController owner, GameObject targetOrbitalPrefab, bool isFollower, PlayerOrbitalItem sourceItem = null)
        {
            GameObject gameObject = UnityEngine.Object.Instantiate<GameObject>(targetOrbitalPrefab, owner.transform.position, Quaternion.identity);
            bool flag = !isFollower;
            if (flag)
            {
                PlayerOrbital component = gameObject.GetComponent<PlayerOrbital>();
                component.Initialize(owner);
                component.SourceItem = sourceItem;
            }
            else
            {
                PlayerOrbitalFollower component2 = gameObject.GetComponent<PlayerOrbitalFollower>();
                bool flag2 = component2;
                if (flag2)
                {
                    component2.Initialize(owner);
                }
            }
            return gameObject;
        }
        public virtual void OnOrbitalCreated(GameObject orbital)
        {

        }

        // Token: 0x060000F7 RID: 247 RVA: 0x0000B618 File Offset: 0x00009818
        private void HandleBreakOnOwnerDamage(PlayerController arg1)
        {
            bool flag = !this;
            if (!flag)
            {
                bool flag2 = this.BreakVFX && this.m_extantOrbital && this.m_extantOrbital.GetComponentInChildren<tk2dSprite>();
                if (flag2)
                {
                    SpawnManager.SpawnVFX(this.BreakVFX, this.m_extantOrbital.GetComponentInChildren<tk2dSprite>().WorldCenter.ToVector3ZisY(0f), Quaternion.identity);
                }
                bool flag3 = this.m_owner;
                if (flag3)
                {
                    this.m_owner.RemovePassiveItem(this.PickupObjectId);
                    this.m_owner.OnReceivedDamage -= this.HandleBreakOnOwnerDamage;
                }
                UnityEngine.Object.Destroy(base.gameObject);
            }
        }

        // Token: 0x060000F8 RID: 248 RVA: 0x0000B6E0 File Offset: 0x000098E0
        private void HandleBreakOnCollision(CollisionData rigidbodyCollision)
        {
            bool flag = this.m_owner;
            if (flag)
            {
                this.m_owner.RemovePassiveItem(this.PickupObjectId);
            }
            UnityEngine.Object.Destroy(base.gameObject);
        }

        // Token: 0x060000F9 RID: 249 RVA: 0x0000B720 File Offset: 0x00009920
        public void DecoupleOrbital()
        {
            this.m_extantOrbital = null;
            bool flag = this.BreaksUponOwnerDamage && this.m_owner;
            if (flag)
            {
                this.m_owner.OnReceivedDamage -= this.HandleBreakOnOwnerDamage;
            }
        }

        // Token: 0x060000FA RID: 250 RVA: 0x0000B76C File Offset: 0x0000996C
        private void DestroyOrbital()
        {
            bool flag = !this.m_extantOrbital;
            if (!flag)
            {
                bool flag2 = this.BreaksUponOwnerDamage && this.m_owner;
                if (flag2)
                {
                    this.m_owner.OnReceivedDamage -= this.HandleBreakOnOwnerDamage;
                }
                UnityEngine.Object.Destroy(this.m_extantOrbital.gameObject);
                this.m_extantOrbital = null;
            }
        }

        // Token: 0x060000FB RID: 251 RVA: 0x0000B7DC File Offset: 0x000099DC
        protected override void Update()
        {
            base.Update();
            bool hasAdvancedUpgradeSynergy = this.HasAdvancedUpgradeSynergy;
            if (hasAdvancedUpgradeSynergy)
            {
                bool flag = this.m_advancedSynergyUpgradeActive && (!this.m_owner || !this.m_owner.PlayerHasActiveSynergy(this.AdvancedUpgradeSynergy));
                if (flag)
                {
                    bool flag2 = this.m_owner;
                    if (flag2)
                    {
                        for (int i = 0; i < this.advancedSynergyModifiers.Count; i++)
                        {
                            this.m_owner.healthHaver.damageTypeModifiers.Remove(this.advancedSynergyModifiers[i]);
                        }
                    }
                    this.m_advancedSynergyUpgradeActive = false;
                    this.DestroyOrbital();
                    bool flag3 = this.m_owner;
                    if (flag3)
                    {
                        this.CreateOrbital(this.m_owner);
                    }
                }
                else
                {
                    bool flag4 = !this.m_advancedSynergyUpgradeActive && this.m_owner && this.m_owner.PlayerHasActiveSynergy(this.AdvancedUpgradeSynergy);
                    if (flag4)
                    {
                        this.m_advancedSynergyUpgradeActive = true;
                        this.DestroyOrbital();
                        bool flag5 = this.m_owner;
                        if (flag5)
                        {
                            this.CreateOrbital(this.m_owner);
                        }
                        for (int j = 0; j < this.advancedSynergyModifiers.Count; j++)
                        {
                            this.m_owner.healthHaver.damageTypeModifiers.Add(this.advancedSynergyModifiers[j]);
                        }
                    }
                }
            }
            bool hasUpgradeSynergy = this.HasUpgradeSynergy;
            if (hasUpgradeSynergy)
            {
                bool flag6 = this.m_synergyUpgradeActive && (!this.m_owner || !this.m_owner.HasActiveBonusSynergy(this.UpgradeSynergy, false));
                if (flag6)
                {
                    bool flag7 = this.m_owner;
                    if (flag7)
                    {
                        for (int k = 0; k < this.synergyModifiers.Length; k++)
                        {
                            this.m_owner.healthHaver.damageTypeModifiers.Remove(this.synergyModifiers[k]);
                        }
                    }
                    this.m_synergyUpgradeActive = false;
                    this.DestroyOrbital();
                    bool flag8 = this.m_owner;
                    if (flag8)
                    {
                        this.CreateOrbital(this.m_owner);
                    }
                }
                else
                {
                    bool flag9 = !this.m_synergyUpgradeActive && this.m_owner && this.m_owner.HasActiveBonusSynergy(this.UpgradeSynergy, false);
                    if (flag9)
                    {
                        this.m_synergyUpgradeActive = true;
                        this.DestroyOrbital();
                        bool flag10 = this.m_owner;
                        if (flag10)
                        {
                            this.CreateOrbital(this.m_owner);
                        }
                        for (int l = 0; l < this.synergyModifiers.Length; l++)
                        {
                            this.m_owner.healthHaver.damageTypeModifiers.Add(this.synergyModifiers[l]);
                        }
                    }
                }
            }
        }

        // Token: 0x060000FC RID: 252 RVA: 0x0000BAD0 File Offset: 0x00009CD0
        public override void Pickup(PlayerController player)
        {
            base.Pickup(player);
            player.OnNewFloorLoaded = (Action<PlayerController>)Delegate.Combine(player.OnNewFloorLoaded, new Action<PlayerController>(this.HandleNewFloor));
            for (int i = 0; i < this.modifiers.Length; i++)
            {
                player.healthHaver.damageTypeModifiers.Add(this.modifiers[i]);
            }
            this.CreateOrbital(player);
        }

        // Token: 0x060000FD RID: 253 RVA: 0x0000243D File Offset: 0x0000063D
        private void HandleNewFloor(PlayerController obj)
        {
            this.DestroyOrbital();
            this.CreateOrbital(obj);
        }

        // Token: 0x060000FE RID: 254 RVA: 0x0000BB44 File Offset: 0x00009D44
        public override DebrisObject Drop(PlayerController player)
        {
            this.DestroyOrbital();
            player.OnNewFloorLoaded = (Action<PlayerController>)Delegate.Remove(player.OnNewFloorLoaded, new Action<PlayerController>(this.HandleNewFloor));
            for (int i = 0; i < this.modifiers.Length; i++)
            {
                player.healthHaver.damageTypeModifiers.Remove(this.modifiers[i]);
            }
            for (int j = 0; j < this.synergyModifiers.Length; j++)
            {
                player.healthHaver.damageTypeModifiers.Remove(this.synergyModifiers[j]);
            }
            return base.Drop(player);
        }

        // Token: 0x060000FF RID: 255 RVA: 0x0000BBEC File Offset: 0x00009DEC
        protected override void OnDestroy()
        {
            bool flag = this.m_owner != null;
            if (flag)
            {
                PlayerController owner = this.m_owner;
                owner.OnNewFloorLoaded = (Action<PlayerController>)Delegate.Remove(owner.OnNewFloorLoaded, new Action<PlayerController>(this.HandleNewFloor));
                for (int i = 0; i < this.modifiers.Length; i++)
                {
                    this.m_owner.healthHaver.damageTypeModifiers.Remove(this.modifiers[i]);
                }
                for (int j = 0; j < this.synergyModifiers.Length; j++)
                {
                    this.m_owner.healthHaver.damageTypeModifiers.Remove(this.synergyModifiers[j]);
                }
                this.m_owner.OnReceivedDamage -= this.HandleBreakOnOwnerDamage;
            }
            this.DestroyOrbital();
            base.OnDestroy();
        }

        public PlayerOrbital OrbitalPrefab;
        public PlayerOrbitalFollower OrbitalFollowerPrefab;
        public bool HasUpgradeSynergy;
        public CustomSynergyType UpgradeSynergy;
        public GameObject UpgradeOrbitalPrefab;
        public GameObject UpgradeOrbitalFollowerPrefab;
        public bool CanBeMimicked;
        public DamageTypeModifier[] modifiers;
        public DamageTypeModifier[] synergyModifiers;
        public bool BreaksUponContact;
        public bool BreaksUponOwnerDamage;
        public GameObject BreakVFX;
        protected GameObject m_extantOrbital;
        protected bool m_synergyUpgradeActive;
        public bool HasAdvancedUpgradeSynergy;
        public string AdvancedUpgradeSynergy;
        public GameObject AdvancedUpgradeOrbitalPrefab;
        public GameObject AdvancedUpgradeOrbitalFollowerPrefab;
        public List<DamageTypeModifier> advancedSynergyModifiers = new List<DamageTypeModifier>();
        protected bool m_advancedSynergyUpgradeActive;
 

Now we make our actual Guon, make sure it inherits from AdvancedPlayerOrbitalItem

drop in:

public static PlayerOrbital orbitalPrefab;
        public static PlayerOrbital upgradeOrbitalPrefab;
        public static void Init()
        {
            string itemName = "Your Guon Stone"; //The name of the item
            string resourceName = "ExampleMod/Resources/yourguon_icon"; //(inventory sprite) MAKE SURE TO CHANGE THE SPRITE PATH TO YOUR MOD'S RESOURCES.

            GameObject obj = new GameObject();
            var item = obj.AddComponent<YourGuonStone>();
            ItemBuilder.AddSpriteToObject(itemName, resourceName, obj);

            string shortDesc = "Short Description";
            string longDesc = "Long Description";

            ItemBuilder.SetupItem(item, shortDesc, longDesc, "yourprefixhere");
            item.quality = PickupObject.ItemQuality.A;

            BuildPrefab();
            item.OrbitalPrefab = orbitalPrefab;
            BuildSynergyPrefab();

            item.HasAdvancedUpgradeSynergy = true; //Set this to true if you want a synergy that changes the appearance of the Guon Stone. All base game guons have a [colour]-er Guon Stone synergy that makes them bigger and brighter.
            item.AdvancedUpgradeSynergy = "Yourer Guon Stone"; //This is the name of the synergy that changes the appearance, if you have one.
            item.AdvancedUpgradeOrbitalPrefab = YourGuonStone.upgradeOrbitalPrefab.gameObject;
        }

        public static void BuildPrefab()
        {
            if (YourGuonStone.orbitalPrefab != null) return;
            GameObject prefab = SpriteBuilder.SpriteFromResource("ExampleMod/Resources/yourguon_ingame"); //(ingame orbital sprite)MAKE SURE TO CHANGE THE SPRITE PATH TO YOUR MODS RESOURCES
            prefab.name = "Your Guon Orbital"; //The name of the orbital used by the code. Barely ever used or seen, but important to change.
            var body = prefab.GetComponent<tk2dSprite>().SetUpSpeculativeRigidbody(IntVector2.Zero, new IntVector2(5, 9)); //This line sets up the hitbox of your guon, this one is set to 5 pixels across by 9 pixels high, but you can set it as big or small as you want your guon to be.           
            body.CollideWithTileMap = false;
            body.CollideWithOthers = true;
            body.PrimaryPixelCollider.CollisionLayer = CollisionLayer.EnemyBulletBlocker;

            orbitalPrefab = prefab.AddComponent<PlayerOrbital>();
            orbitalPrefab.motionStyle = PlayerOrbital.OrbitalMotionStyle.ORBIT_PLAYER_ALWAYS; //You can ignore most of this stuff, but I've commented on some of it.
            orbitalPrefab.shouldRotate = false; //This determines if the guon stone rotates. If set to true, the stone will rotate so that it always faces towards the player. Most Guons have this set to false, and you probably should too unless you have a good reason for changing it.
            orbitalPrefab.orbitRadius = 2.5f; //This determines how far away from you the guon orbits. The default for most guons is 2.5.
            orbitalPrefab.orbitDegreesPerSecond = 120f; //This determines how many degrees of rotation the guon travels per second. The default for most guons is 120.
            orbitalPrefab.perfectOrbitalFactor = 0f; //This determines how fast guons will move to catch up with their owner (regular guons have it set to 0 so they lag behind). You can probably ignore this unless you want or need your guon to stick super strictly to it's orbit.
            orbitalPrefab.SetOrbitalTier(0);

            GameObject.DontDestroyOnLoad(prefab);
            FakePrefab.MarkAsFakePrefab(prefab);
            prefab.SetActive(false);
        }
        public static void BuildSynergyPrefab()
        {
            bool flag = YourGuonStone.upgradeOrbitalPrefab == null;
            if (flag)
            {
                GameObject gameObject = SpriteBuilder.SpriteFromResource("ExampleMod/Resources/yourguon_synergy", null); //(The orbital appearance with it's special synergy) MAKE SURE TO CHANGE THE SPRITE PATH TO YOUR OWN MODS
                gameObject.name = "Your Guon Orbital Synergy Form";
                SpeculativeRigidbody speculativeRigidbody = gameObject.GetComponent<tk2dSprite>().SetUpSpeculativeRigidbody(IntVector2.Zero, new IntVector2(9, 13));
                YourGuonStone.upgradeOrbitalPrefab = gameObject.AddComponent<PlayerOrbital>();
                speculativeRigidbody.CollideWithTileMap = false;
                speculativeRigidbody.CollideWithOthers = true;
                speculativeRigidbody.PrimaryPixelCollider.CollisionLayer = CollisionLayer.EnemyBulletBlocker;
                YourGuonStone.upgradeOrbitalPrefab.shouldRotate = false; //Determines if your guon rotates with it's special synergy
                YourGuonStone.upgradeOrbitalPrefab.orbitRadius = 2.5f; //Determines how far your guon orbits with it's special synergy
                YourGuonStone.upgradeOrbitalPrefab.orbitDegreesPerSecond = 120f; //Determines how fast your guon orbits with it's special synergy
                YourGuonStone.upgradeOrbitalPrefab.perfectOrbitalFactor = 10f; //Determines how fast your guon will move to catch up with its owner with it's special synergy. By default, even though the regular guons have it at 0, the upgraded synergy guons all have a higher perfectOrbitalFactor. I find 10 to be about the same.
                YourGuonStone.upgradeOrbitalPrefab.SetOrbitalTier(0);
                UnityEngine.Object.DontDestroyOnLoad(gameObject);
                FakePrefab.MarkAsFakePrefab(gameObject);
                gameObject.SetActive(false);
            }
        }
        protected override void Update()
        {
            base.Update();
        }
        public override void Pickup(PlayerController player)
        {
            base.Pickup(player);
        }
        public override DebrisObject Drop(PlayerController player)
        {
            return base.Drop(player);
        }
        protected override void OnDestroy()
        {
            base.OnDestroy();
        }

read the comments to understand how it works.