In a Commander game, does damage dealt by your commander to a player count toward commander damage even if a pump spell increased its power?

Commander damage tracks the total combat damage a specific commander deals to each player over the course of the game. According to the Commander rules (based on CR 903.10a in conjunction with official Commander format rules), 21 or more combat damage dealt by a single commander to a player results in that player losing the game.

The source of any power increase — whether a pump spell like Giant Growth, an Equipment, an Aura, or a static ability — does not matter. What matters is that the damage was dealt in combat by your commander. The game tracks the commander as the damage source, not its base power. Per CR 510.2, combat damage is assigned based on a creature's power at the time damage is assigned, and that full amount is credited to the commander's damage total.

There is no rule that distinguishes 'natural' power from 'pumped' power for the purpose of commander damage tracking. All combat damage from the commander counts equally, regardless of what modified its power (CR 903.10a).

Concrete example: Your commander has 3 power. Before it deals combat damage, you cast Unleash Fury, doubling its power to 6. It deals 6 combat damage to a player. All 6 points count as commander damage. After three such attacks (assuming no other damage), that player has taken 18 commander damage and is 3 away from losing.

Note: Only combat damage counts toward commander damage. If your commander deals damage via a non-combat ability (e.g., a triggered or activated ability), that damage does not count toward the 21-damage threshold, pumped or not (CR 903.10a).