Citadel Siege

The mode-on-entry choice is the whole design decision here, and it splits the card into two unrelated jobs that share a frame and a cost. Pick Khans and you have a recurring anthem engine: two counters on a creature at the start of combat on your turn, no activation cost, no tapping required, the kind of accelerating clock that turns a single threat into a problem within a few turns. Pick Dragons and the same enchantment becomes a defensive lock, tapping down an attacker before each opponent's combat to neuter their best creature on a permanent loop. One mode is for the player ahead on board; the other is for the player trying to stay alive. You commit at the moment it resolves, with no way to switch later, and that irreversibility is what pays for getting two genuinely strong abilities in one slot. What makes the choice sharp is that the timing windows differ: the Khans trigger fires only on your own combat and rewards a developed board, while the Dragons trigger fires on each opponent's turn and scales with how many opponents you face, doing more work the more attackers are pointed at you. Most modal permanents hedge by offering small variations on a theme; this one offers a buildaround anthem and a soft prison, then leaves the read to you before it enters.