The mulligan rule has undergone three major revisions since its introduction to tournament play
Boggart Cursecrafter Boltwave Booby Trap Boomerang, Blade Flinger Brallin, Skyshark Rider Brazen Cannonade Brazen Dwarf Breath of Malfegor Brimstone Trebuchet Brimstone Vandal Broodbirth Viper Bulwark Burning Cinder Fury of Crimson Chaos Fire Burning of Xinye Cabal Paladin Cartouche of Strength Catti-brie of Mithral Hall Cavalier of Flame Cavern-Hoard Dragon Cerebral Eruption Chainer's Torment Champion of the Path Chandra's Ignition Chandra, Awakened Inferno Chandra, Flame's Catalyst Chandra, Legacy of Fire Chandra, Pyrogenius Chandra, Roaring Flame Chandra, Torch of Defiance Chelonian Tackle Circle of Power Collective Defiance Colossus of the Blood Age Commodore Guff Conclave Evangelist Contested Cliffs
the flashback mechanic), from the top of your library (Future Sight), or from exile (Reckless Impulse)
One is a ten-card cycle of life-gain lands that enter tapped and give you 1 life
World Breaker Creatures that kill something when they come into play are always powerful
Make sure to check them out as well