Boilt, Sire of Treecave

At the beginning of your end step, you may tap
Boilt, Sire of Treecave. If you do, Amalgamate X
where X is the number of creature cards in your graveyard (To Amalgamate, you must have the same
number of basic land as target opponent. If you don't,
the Amalgamate fails. If you do, lands you control
provide any one type of mana until end of turn. Spells
you cast cost any one color mana.)
It always wants to combine things, making them into mysterious mutants.