Guilds of Ravnica

Chance for Glory | Instant | | Creatures you control gain indestructible. Take an extra turn after this one. At the beginning of that turn's end step, you lose the game. | Bram Sels

Justice Strike | Instant | | Target creature deals damage to itself equal to its power. | Clint Cearley

Integrity | Instant | | Target creature gets +2/+2 until end of turn. | Ben Maier

Response | Instant | | Response deals 5 damage to target attacking or blocking creature. | Daarken

Join Shields | Instant | | Untap all creatures you control. They gain hexproof and indestructible until end of turn. (They can't be the targets of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy them.) | Winona Nelson

March of the Multitudes | Instant | | Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) Create X 1/1 white Soldier creature tokens with lifelink. | Zack Stella

Assure | Instant | | Put a +1/+1 counter on target creature. That creature gains indestructible until end of turn. | Jason A. Engle