Whenever one or more other permanents phase out and whenever one or more other cards are put into exile from anywhere, put a time counter on The War Doctor.
Whenever The War Doctor attacks, it deals damage equal to the number of time counters on it to any target. If a creature dealt damage this way would die this turn, exile it instead.
The War Doctor is a counters-as-damage attacker: you stockpile time counters by repeatedly phasing permanents out and exiling cards, then swing to fire off a growing burst that snipes creatures, planeswalkers, or faces. Early turns are spent building a phase/exile engine and protecting the Doctor, mid-game you exile from everywhere to balloon the counter, and you close by attacking for lethal direct damage. As a Doctor, he wants a Doctor's Companion in the command zone for added value and resilience.
Counters never go away, so damage scales relentlessly across a long game
Hits any target, doubling as removal, planeswalker control, and reach to the dome
The exile clause replaces dies-triggers, denying graveyard recursion to opponents
Cheap to cast at four mana and benefits from both phasing and exile, two underexplored axes
Doctor's Companion gives a free second commander for extra engine pieces
Does nothing the turn it lands and needs to connect to matter, so it's vulnerable to removal and blockers
Counter buildup is slow without a dedicated phase/exile engine
Heavily commander-dependent; repeated bounces or board wipes reset your clock
No card advantage built in, so RW hand refill must come from the 99
Single large attack can be fogged or chump-blocked to fizzle lethal
Legendary Creature — Time Lord Doctor
