Oath of Ajani

The two halves point at completely different decks, and that split is the whole tension here. The enters trigger is an aggro payoff: a board-wide counter that rewards a flooded battlefield, the kind of effect that wants creatures already deployed when you cast it. The static ability is a control-and-superfriends incentive, shaving a generic mana off every planeswalker you cast, the kind of effect that wants a deck thin on creatures and heavy on the loyalty engine. A pure aggro deck has few planeswalkers to discount; a planeswalker deck rarely fields enough creatures for the counters to matter. The card asks for a middle build that fields a wide enough board to justify the trigger and runs enough planeswalkers to bank the discount, which in practice means a creature-leaning Green-White shell that treats walkers as its top end rather than its core. The cost reduction also compounds in a way the counter does not: every walker you resolve afterward is cheaper, so the static half is the one that scales with the game while the trigger is a one-time burst on arrival. It is named for a planeswalker and built to enable planeswalkers, but the body of the card is most at home alongside creatures, and reconciling that pull is the deckbuilding problem it sets.