(A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.) Whenever a nontoken creature is put into your graveyard from the battlefield, you may pay
That said, some hawk-eyed readers will notice some odd card choices in this list
Just make sure that the card you're interested in is legitimate before you buy it
It doesnt even have to be in those decks, quite frankly
Astral Cornucopia $2 Ill likely swap out Darksteel Ingot for this in some of my Commander decks that can ramp really high, but very few ramp decks are going to want to sink even six mana into this
That is exactly what Energy Removal, and its counterpart, Super Energy Removal, inflicts on Pokmon TCG players