Mistveil Researcher

If {g} was used to cast Mistveil Researcher,
place a +1/+1 Counter on target creature.
If {u} was used to cast Mistveil Researcher,
place a -1/-1 Counter on target creature.
If {g} and {u} were used to cast Mistveil Researcher, target creature gains Vigilance and First Strike until end of turn.