At the beginning of combat on your turn, put a number of +1/+1 counters equal to Jenova's power on up to one other target creature. That creature becomes a Mutant in addition to its other types.
Whenever a Mutant you control dies during your turn, you draw cards equal to its power.
Jenova snowballs a single creature with explosive +1/+1 counter growth—each combat she dumps counters equal to her own power, and a doubling effect makes the recipient (now a Mutant) huge fast. Then you cash those over-pumped Mutants in through sacrifice outlets to draw a massive grip of cards on your turn, refueling toward a lethal swing or combo. Turn to turn you protect Jenova, grow a threat, and convert board state into cards and damage.
Built-in card advantage engine—dying Mutants draw cards equal to power, which scales absurdly with counters
Exponential power growth when paired with counter-doublers, turning any creature lethal in a turn or two
Operates in the deep BG toolbox of ramp, recursion, removal, and sacrifice outlets
Self-sufficient commander that needs little support to start generating value
Heavily commander-dependent; if Jenova is removed the counter engine stalls
Targeted removal or sacrifice forced on the pumped Mutant erases your investment for no payoff
Slow to come online without acceleration—first activation only adds power equal to Jenova's 2 base
No evasion or protection baked in, so a single blocker or wrath sets you way back
Two-color identity lacks card filtering and burst interaction of other shells
Legendary Creature — Alien
