Each Sliver creature card in your graveyard has unearth {2}.
Unearth {2} ({2}: 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.)
“A colony of horrors lurks beneath the mire. One must move deliberately with every ste—”
—Loamlair guide, last words