Royal Tournament

{2}{t}: Target creature you control fights target
creature. If your creature kills the opposing
creature without dying, that creature gains a
+1 +1 counter. If you pay an additional {2}, any
player may activate this ability.
"In the Royal Tournaments, even the Imperians are
invited, so long as they maintain the ceasefire.
Friends fight friends, friends fight enemies,
and enemies fight enemies."