Recursion is rather easy with Summon: Titan being able to put all lands into the battlefield from the graveyard, Evil Reawakened able to put any creatures back onto the battlefield, and Fight On
I also have to give a shout-out to the flavor text on each version of the card, offering different takes on the way that this spell tends to play out when cast
Sol Ring is an obvious example of this trend
Steelbane Hydra Besides being equal to almost all hydras, Steelbane Hydra does something very different in being a Naturalize
Whenever it attacks, if the defending player has more cards in their hand than you do, you get to exile the top card of their library and play it on any turn you attack with a rogue
The single most important card in the game for me was probably Three Tree City, in that my pivotal turns in the late game were made possible by the extra mana I got from that amazing land