As much as everyone said they hated universes beyond, being able to play Tifa and Cloud in mtg quickly changed a lot of mind
Voice of VictoryVoice of Victory is by far the best mobilize card: It's cheap to cast, fairly resilient, it gives you the counterspell-pass for your turns, and it also prepares you coffee (it doesn't, but it may as well do)
Creatures that make mana (mana dorks), artifacts that make mana (mana rocks), Rampant GrowthRampant Growth-type effects, "rituals" like Dark RitualDark Ritual, cards that make Treasure tokens
Cards like Archetype of Endurance and Sigarda, Host of Herons can provide broad protection for your entire board
11I think the better phrase would be, "you almost always wouldn't." A number of great players have, on rare occasions, played 61 cards and done well with them, though obviously they put a great deal of thought into the matter