Guilds of Ravnica

Sunhome Stalwart | Creature | Human Soldier | First strike Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) | Matt Stewart

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

Conclave Guildmage | Creature | Elf Cleric | {G}, {T}: Creatures you control gain trample until end of turn. {5}{W}, {T}: Create a 2/2 green and white Elf Knight creature token with vigilance. | Jason Rainville

Worldsoul Colossus | Creature | Elemental | 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.) Worldsoul Colossus enters the battlefield with X +1/+1 counters on it. | James Paick