Whenever Qala attacks, other attacking creatures you control get +X/+0 until end of turn, where X is the number of counters on Qala.
Whenever you gain life, put a +1/+1 counter on Qala.
: You gain 1 life.
Qala is a mono-white aggressive lifegain commander: gain life to stack +1/+1 counters on her, then attack to pump your whole team by the counter count. You build a wide board of lifegain payoffs and aggressive creatures, snowball Qala's counters fast, and swing for lethal once the anthem effect gets out of hand.
Snowballs incredibly fast since every lifegain trigger (not just per turn) adds a counter
Provides a built-in team anthem that scales with little effort
Self-contained mana sink with her ability for late-game inevitability
Lifegain offers a strong defensive cushion while you build the board
Mono-white means weak card draw and no built-in ramp beyond rocks
Heavily commander-dependent; her removal stalls the whole offense
Counter and creature wipes (Cyclonic Rift, board wipes) reset your snowball
Lifegain alone doesn't win—you need the attack triggers to actually convert