Hallows Eve Fiend

Whenever another nontoken plant creature
enters the battlefield under your control you may
pay X and sacrifice it, if you do, put X +1+1
counters on Hallows Eve Fiend, where X is that
cards converted mana cost.
{1}{b}{r}{g}, Sacrifice a plant you control: Hallows
Eve Fiend gains trample, menace or first strike.
"Stomps and screams could be heard throughout
the night"