Reroute Systems

The two halves point in opposite directions, and that asymmetry is the whole design. The first mode is pure protection: a one-mana instant that hands indestructible to anything worth keeping, the kind of insurance you leave open on a critical creature or your key artifact. The second is a conditional Shock that only fires at tapped creatures, which quietly rewrites when you cast it. You want an attacker or a tapper already committed elsewhere, so the removal half is priced for reactive play into an aggressive opponent rather than a proactive kill. Bundling those two jobs into one card is the trick. Protection spells sit dead in your hand against passive draws; narrow removal sits dead against defensive ones. A modal split lets the card stay live in both directions, so the mana you hold up open is never wasted no matter which way the game breaks. The tapped-creature restriction is doing more work than the two damage suggests: it cannot snipe a fresh blocker or a planeswalker's defender, only something already spent on combat or an activated ability. That single word turns a generic burn spell into a specifically reactive one, rewarding the player patient enough to let the opponent tap out first before deciding which mode the card needs to be.