Doctor's companion (You can have two commanders if the other is the Doctor.)
Adric copies your best activated and triggered abilities, doubling value engines like draw triggers, mana abilities, and ETB/attack triggers. As a Doctor's companion he's almost always paired with a blue-inclusive Doctor partner, so you build around stacking and replaying triggers while protecting Adric, then convert that snowballing card and resource advantage into a combo or overwhelming board. His Ultimate Sacrifice doubles as interaction by countering a key activated or triggered ability.
Doubles the value of any activated/triggered ability you control, turning good engines into game-warping ones
Built-in interaction: can counter an opponent's crucial activated or triggered ability by sacrificing
Doctor's companion gives access to a second commander, widening colors and strategies
Cheap to cast at 2 mana, so he comes down early and recovers quickly
Repeatable copy effect with new targets enables flexible value and combos
Mono-blue on his own lacks ramp and removal depth; leans heavily on the paired Doctor
Copy ability costs and a tap, which is mana-intensive and slow each turn
Vulnerable to removal—losing Adric stalls the whole engine
Needs a critical mass of strong abilities to be worth the activation cost
Telegraphs combos, inviting interaction and being targeted first
Stacks with Adric to copy triggered abilities multiple times for runaway value.
Pick a high-impact blue Doctor partner that generates repeatable triggers (suspend, time counters, or ETB value) so Adric always has targets. Add cheap protection (Swiftfoot Boots, Mother of Runes-style effects, counterspells) and fast mana (Sol Ring, Mana Crypt, signets) to power the activation each turn. Tighten toward a dedicated combo finish—Isochron Scepter loops, Aetherflux Reservoir, or extra-turn chains—rather than diffuse value.