At the beginning of your end step, if you didn't cast any spells this turn, Howltooth Slagheap deals 1 damage to you.
When Howltooth Slagheap enters the battlefield, put a land you control on the bottom of its owner's library.
: Add 
to your mana pool.
,
, Sacrifice Howltooth Slagheap: Target player gets a poison counter.