Boros Recruit

({R/W} can be paid with either {R} or {W}.)
First strike

Scourge of the Nobilis

Enchant creature
As long as enchanted creature is red, it gets +1/+1 and has "{R/W}: This creature gets +1/+0 until end of turn."
As long as enchanted creature is white, it gets +1/+1 and has lifelink. (Damage dealt by the creature also causes its controller to gain that much life.)

Make Your Mark

Target creature gets +1/+0 until end of turn. When that creature dies this turn, create a 3/2 red and white Spirit creature token.

Battlegate Mimic

Whenever you cast a spell that's both red and white, Battlegate Mimic has base power and toughness 4/2 until end of turn and gains first strike until end of turn.

Cerodon Yearling

Thrilling Discovery

You gain 2 life. Then you may discard two cards. If you do, draw three cards.

Duergar Assailant

Sacrifice Duergar Assailant: It deals 1 damage to target attacking or blocking creature.

Tenth District Legionnaire

Haste
Whenever you cast a spell that targets Tenth District Legionnaire, put a +1/+1 counter on Tenth District Legionnaire, then scry 1.