Guilds of Ravnica

Boros Challenger | Creature | Human Soldier | Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) {2}{R}{W}: Boros Challenger gets +1/+1 until end of turn. | Gabor Szikszai

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

Legion Guildmage | Creature | Human Wizard | {5}{R}, {T}: Legion Guildmage deals 3 damage to each opponent. {2}{W}, {T}: Tap another target creature. | Zack Stella

Swiftblade Vindicator | Creature | Human Soldier | Double strike, vigilance, trample | Viktor Titov

Fresh-Faced Recruit | Creature | Human Soldier | As long as it's your turn, Fresh-Faced Recruit has first strike. | Anthony Palumbo

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