Woman Who Walked the Earth — When Martha Jones enters, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, Martha Jones and up to one other target creature can't be blocked this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)
Pair Martha with a Doctor partner (usually a Time Lord that rewards combat damage or card draw) and use Clue tokens both as card advantage and as repeatable unblockable enablers. You sacrifice Clues to draw and to push Martha or a beater through unblocked, grinding value while threatening lethal evasive damage. The deck plays a midrange artifact/value game and closes by making a single creature impossible to stop.
Built-in card advantage from the entry Clue plus any Clue payoffs
Repeatable, flexible unblockable for Martha or a key threat enables commander damage and combat triggers
Mono-blue access to counterspells, card draw, and bounce for a resilient game plan
Doctor's companion lets you build a two-commander deck with strong color/strategy fit
Unblockable does nothing against board wipes, removal, or fog effects
Mono-blue lacks efficient creature removal and struggles against go-wide token swarms
Martha and the chosen creature still die to damage-based or sacrifice-based blocks aren't the issue, but combat tricks/blink can blank the attack
Reliant on having Clues to sacrifice and on the Doctor partner for damage payoffs
Generates Clue-like artifacts; any sac fodder feeds Martha's unblockable trigger.
Add more Clue and artifact-token doublers (Academy Manufactor, Tireless Provisioner) and cheap sac outlets so unblockable triggers come every turn for near-free. Tighten the manabase with fast mana and fix the curve, then lean into a real voltron package—equipment, evasion redundancy, and protection like Swiftfoot Boots and counterspells—or a combat-trigger swarm so each unblocked hit converts to overwhelming value or lethal commander damage.