Large spells advance the game plan while also threatening opponents at random, which creates tension at the table
Then, at the beginning of your combat step, you can pay three energy to create a copy of one of your permanents, make it a 5/5, and sacrifice it at the beginning of the next end step
Omnath doubles as both a mana ramp and a giant threat, while the two Nissas both ramp and attack later on
Every week, I gaze balefully at the perpetually empty "Planeswalker" subcategory of my deck template, yearning for the day that I will stuff it to the brim with planeswalkers
Its synergy with card draw mechanics makes it a consistent source of pressure, and its power and toughness scaling with your hand size makes it a formidable presence on the battlefield as well
As Kaladesh spoilers are already in full swing (actually kind of winding down at this point, although were still missing quite a few of the story moments as of this writing), it seems like a good chance to look back at Shadows over Innistrad