For only one mana with
Training Grounds, The Scarab-God's activated ability pass from kinda slow but useful to a really good instant speed
reanimate. Lowering the cost of this activated ability, permit easier instant speed interaction with creature like
hostage taker, cheap gravehate and building a army of 4/4 creature a lower cost.
Otherwise cheap tutors like
vampiric tutor and
Demonic tutor are always good option of course but i try to avoid them because of their price and they push the game in a straightforward direction while I like when each game feel different.