Hour of Need

The trick is in which direction the trade runs. Exiling a creature and replacing it with a 4/4 flier is an upgrade or a downgrade depending entirely on whose creature you point it at: aim it across the table at something large and resource-intensive, and you have answered a serious threat by handing the opponent a plain 4/4 flying Sphinx in its place, stripping any counters, auras, or graveyard payoff the original had bolted on, since the token is a fresh object carrying none of the old card's text or modifications. Aim it at your own small body (a token, a one-drop, anything that has done its job) and you have converted spare board presence into evasive damage at a clean rate. Strive is what lets the spell scale to both jobs at once, exiling several creatures in one cast so you can downgrade a couple of opposing threats and upgrade one of your own in the same instant. Note what the exile does and does not buy: it shuts off death triggers, but the creature still leaves the battlefield, so anything keyed to that event will still fire. Instant speed keeps both modes live in combat: pull a blocker before damage, or answer a removal spell aimed at your creature by trading its identity for a flier in response. It is a niche tool wearing the silhouette of a board wipe, dead against three modest creatures and genuinely warping against the right one or two.