Swift Arachnid

When Swift Arachnid enters the battlefield, creatures you control gain first strike until end of turn.
Unearth {2}{b}{g}({2}{b}{g}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)
Scavenge {2}{b}{g}({2}{b}{g}, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)