When Tanazir Quandrix enters, double the number of +1/+1 counters on target creature you control.
Whenever Tanazir Quandrix attacks, you may have the base power and toughness of other creatures you control become equal to Tanazir Quandrix's power and toughness until end of turn.
Build a wide board of creatures and stack +1/+1 counters, then deploy Tanazir to double them on a key threat. Attack to copy Tanazir's huge power/toughness onto your whole team for a one-shot alpha strike, ideally with trample or evasion. The deck plays as a Simic counters midrange/go-wide hybrid that snowballs from incremental growth into a lethal swing.
Doubling counters on a single creature can instantly create a massive, hard-to-block threat
The attack trigger turns even small tokens into copies of a giant body for explosive damage
Green/blue offers premier counter synergies, ramp, and card draw to fuel the engine
Flying and trample make Tanazir itself a reliable evasive finisher
Relies on creatures surviving to the combat step—wraths and removal reset everything
The big payoff swing is telegraphed and vulnerable to a single instant-speed answer
No built-in evasion for the rest of the team, so the power-copy can be chump-blocked
Doubling zero counters does nothing, so you need setup before Tanazir matters
Turns the power-copy attack into an infect/poison shortcut for a fast unexpected win.
Add more counter doublers (Hardened Scales, Branching Evolution, Doubling Season) and proliferate engines to make the doubling trigger lethal faster. Improve evasion and protection—Heroic Intervention, Snakeskin Veil, and trample-granters like Rancor or Inkmoth—so your one-big-swing doesn't get blown out. Tighten the curve with efficient ramp (Sol Ring, Birds of Paradise) and a dedicated overrun finisher to convert board states the same turn.