Oath of Teferi

Doubling planeswalker activations is one of the loudest things a permanent can do, and the second clause here states it flatly: two loyalty activations per planeswalker, every turn. That is the value engine, but the enters-the-battlefield clause is the more telling design choice. The forced blink of another permanent you control is not pure upside; it is a built-in cost, and a clumsy one in many board states (you have to have a useful target, and the blinked permanent leaves until the end step). Read generously, though, the blink is a feature: flicker a planeswalker you already control and it returns at full base loyalty, ready to be activated twice the following turn, so the two halves of the card feed each other. The static ability is also where the power lives in any deck stacking multiple walkers, because it scales with the board rather than the card: one Oath of Teferi turns a table of three planeswalkers into six activations. Compared to the older approach of doubling a single resource (counters, tokens, mana), this doubles the permission itself, the once-per-turn restriction printed on every planeswalker since the card type debuted. The restriction was always the quiet tax that kept loyalty abilities honest; this lifts it wholesale, which is why the card reads as a build-around rather than a role-player.