The ability to pick up a land made it an instant role-player in any decks running Wasteland or Strip Mine, and the pinging effect fields out a lot of one-toughness competition in formats where Wrenn runs free
You don't have to discard this Energy to make the attack, unless it says so
With more card draw, you can control games with cards like Organic Extinction, play huge spells like Wake the Past, and get your big creatures and planeswalkers like Brudiclad, Telchor Engineer and Ugin, Eye of the Storms more reliably
Number 55 Language English Legal Formats Commander, Legacy, Modern, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Pauper, Pioneer, Standard, Timeless Rulings (7/1/2012) The effect is based on the number of Swamps you control when Mutilate resolves