Has Stompy

local Mod = RegisterMod("yourMod", 1)
local game = Game()

local stompyItems = 0    -- countes the itmes needed for the transformation
local stompyPills = 0    -- countes the pilles needed for the transformation
local Has = {
    Stompy = false    -- will be set to true if the player has the transformation
}

function Mod:detectStompy(player)

    local entities = Isaac.GetRoomEntities()

    -- look for items which contributes to the stompy transformation
    for e = 1, #entities do    -- go though all the entities in the room
        local entity = entities[e]
        if entity.Type == EntityType.ENTITY_PICKUP
        and entity.Variant == PickupVariant.PICKUP_COLLECTIBLE then    -- look for items

            -- check if the item is Magic Mush
            if entity.SubType == CollectibleType.COLLECTIBLE_MAGIC_MUSHROOM then
                if (player.Position - entity.Position):Length() < player.Size + entity.Size    -- pick up detection code
                and not player:HasCollectible(CollectibleType.COLLECTIBLE_MAGIC_MUSHROOM)      -- make sure that the player hasn't picked up the item already
                then
                    stompyItems = stompyItems + 1
                    Mod:SaveData(stompyItems)
                end
            end

            -- check if the item is Leo. We do the same stuff as for Magic Mush
            if entity.SubType == CollectibleType.COLLECTIBLE_LEO then
                if (player.Position - entity.Position):Length() < player.Size + entity.Size    -
                and not player:HasCollectible(CollectibleType.COLLECTIBLE_STOMPY) then
                    stompyItems = stompyItems + 1
                    Mod:SaveData(stompyItems)
                end
            end
        end
    end

    -- check if the player has the Stompy transformation
    if (stompyItems + stompyPills) >= 3 then    -- taking three 'One makes your larger'-pills or take one pill and have two size increasing items will transform Isaac into Stompy
        Has.Stompy = true    -- confirm that the player has the Stompy transformation
    end

    if Has.Stompy == true then  -- if the player has the transformation
        -- then we do stuff
    end
end
Mod:AddCallback(ModCallbacks.MC_POST_PEFFECT_UPDATE, Mod.detectStompy)

-- check if the player takes a 'One makes you larger'-pill
function Mod:countPills(_PillEffect)
    if stompyPills < 3 then    -- only 3 three pills are needed for the transformation
        stompyPills = stompyPills + 1    -- counts your 'One makes you larger'-pills
        Mod:SaveData(stompyPills)
    end
end
Mod:AddCallback(ModCallbacks.MC_USE_PILL, Mod.countPills, PillEffect.PILLEFFECT_LARGER)