Masterful Flourish

Black almost never gets to say "indestructible." The color's whole answer to death has always been to embrace it: sacrifice for value, recur from the graveyard, drain a little life on the way out. Handing black a single-mana instant that shrugs off destruction and combat damage alike is a small heresy, and the heresy is deliberate. It reads as a color-pie loan from white's protection suite or green's Ranger's Guile school of tricks, rebuilt around black's instinct to survive combat rather than avoid it. The +1/+0 is not a rounding error; it turns an even trade into a win, so the card folds offense and insurance into the same mana. The window is the whole game here: cast it in response to a removal spell, in the middle of a block, or as the setup for an alpha strike, and each use bends a different phase in your favor. Its limit is the toughness it leaves untouched: this saves your attacker from burn and a blocker, but a sweeper that says "destroy" is stopped while an "exile" or a "-X/-X" board wipe still gets there. That gap is the seam the design lives in, and it is exactly the kind of seam black is supposed to have.