Tazri, Stalwart Survivor

A convoluted engine card hiding behind an ordinary body. The static ability grants every creature you control a hyper-restricted mana source: it can only pay for creature ability activations, and only if the tapping creature itself has another activated ability. That double qualification is the entire design puzzle. It is not a generic mana rock stapled to your board; it turns a battlefield of activated-ability creatures into a self-contained mana network that funds itself, letting a wide board of dorks and hatebears power up each other's costs without touching your lands. The five-color activated ability is the payoff the static side is built to feed: a Warrior toolbox that mills five and rakes back every creature with a nonmana activated ability, refilling the exact kind of board the mana engine wants. The tension is that both halves want the same thing (a table full of creatures with tappable abilities), so the card rewards a deck built around a single mechanical axis rather than a pile of good cards. This is a very different Tazri from the ally-tribal commander that shares the name; the older version cared about creature types, this one cares about the grammar of activated abilities. That focus is the whole appeal and the whole limitation: assemble the right creatures and it becomes a recursive mana-and-refill loop, but it does almost nothing across a board that lacks activated abilities to feed.