Teval exacts a toll for casting spells, making it so you lose life equal to its mana value, and thats for everything, not just spells you cast with a delve cost
The only thing you have to watch out for is having enough black mana producing lands to cast Darkblast multiple times in a single turn
Krenko sees most play in the Commander format where decks can find ways to activate him multiple times in one turn
As this archetype cares about spells and creatures, the Adventure mechanic plays a big role
Kefka's Tower / Bolas's Citadel (FIC) $15 The only card listed here above $15 that wasn't originally on this list is the Kefka's Tower reskin of Bolas's Citadel, which is a testament to just how dangerous this card is in Commander (and even some Vintage Cubes thanks to Tinker!)
It didnt disappoint, with an audiovisual design and production values that were simply jaw-dropping at the time of release, with many elements that have stood the test of time