Wulf

Swapping the false to true in OnEntityTakeDamage in SpawnMini.cs will fix the issue. As an alternative, the plugin could nullify the damage rather than returning the hook.

So looking at this I should change change this 
object OnEntityTakeDamage(BaseCombatEntity entity, HitInfo info)
{
if (entity == null || info == null || entity.OwnerID == 0)
return null;

if (_data.playerMini.ContainsValue(entity.net.ID))
if (permission.UserHasPermission(entity.OwnerID.ToString(), _noDecay) && info.damageTypes.Has(Rust.DamageType.Decay))
return false;

return null;
}

to

object OnEntityTakeDamage(BaseCombatEntity entity, HitInfo info)
{
if (entity == null || info == null || entity.OwnerID == 0)
return null;

if (_data.playerMini.ContainsValue(entity.net.ID))
if (permission.UserHasPermission(entity.OwnerID.ToString(), _noDecay) && info.damageTypes.Has(Rust.DamageType.Decay))
return true;

return null;
}

(11:19:28) | Calling hook OnEntityTakeDamage resulted in a conflict between the following plugins: SpawnMini - False (Boolean), NoDecay (True (Boolean))

Thanks