local MawMod = RegisterMod("Your Mod", 1);
local game = Game()

local specialTear = {
    BASE_CHANCE = 10,       -- chance for tear to turn into a special one
    MAX_LUCK = 10,          -- max luck requiered to turn every tear into a special one
}

function MawsMod:onUpdate(player)
    for _, entity in pairs(Isaac.GetRoomEntities()) do  -- go through every entity in the room
       if entity.Type == EntityType.ENTITY_TEAR        -- its a tear!
       and entity.SpawnerType == EntityType.ENTITY_PLAYER then
           local tear = entity:ToTear()
           local tearData = tear:GetData()
           local sprite = tear:GetSprite()
           if tearData.NewTear == nil then -- has no data applied to it yet
               -- get rng
               local rng = player:GetCollectibleRNG(CollectibleType.COLLECTIBLE_YOUR_ITEM)
               local roll = rng:RandomInt(100)
               -- will the tear be a variant (based on luck)
               if roll <= ((100 - specialTear.BASE_CHANCE) * player.Luck / specialTear.MAX_LUCK) + specialTear.BASE_CHANCE then
                   -- make sure it's not choas card or bobs rotten head before changing the variant
                   if tear.Variant ~= TearVariant.CHAOS_CARD
                   and tear.Variant ~= TearVariant.BOBS_ROTTEN_HEAD then
                       -- change tear variant
                       -- make sure the tear doesn't is the same variant as the variant you would like to change it to (if you do the tear gets invisible)
                       if tear.Variant ~= TearVariant.BLUE
                       and tear.Variant ~= TearVariant.BLOOD then
                           tearData.NewTear = 1
                           -- change tear variant
                           tear:ChangeVariant(TearVariant.BLUE)
                           -- give it your new spritesheet
                           sprite:ReplaceSpritesheet(0, "gfx/effects/your_new_spritesheet.png")
                           sprite:LoadGraphics()
                       else
                           -- it's already the variant you need
                           tearData.NewTear = 1 -- now your special tear
                           -- give it your new spritesheet
                           sprite:ReplaceSpritesheet(0, "gfx/effects/your_new_spritesheet.png")
                           sprite:LoadGraphics()
                       end
                   end
               end
            elseif tearData.NewTear == 1 then -- your new special tear
                for _, entities in pairs(Isaac.GetRoomEntities()) do
                    if entities:IsActiveEnemy()
                    and not (entities:IsBoss()) then
                        local enemy = entities
                        -- check collision
                        if (enemy.Position:Distance(tear.Position) < 30) then
                        -- if (enemy.Position - tear.Position):Length() <= enemy.Size + tear.Size then
                           -- inflict bleeding
                           enemy:AddEntityFlags(EntityFlag.FLAG_BLEEDING)
                        end
                    end
                end
            end
        end
    end
end
MawMod:AddCallback(ModCallbacks.MC_POST_PEFFECT_UPDATE, MawMod.onUpdate)