Untap, upkeep, draw, Island, Mistform Ultimus! Done.
Oversoul: 20
Hand: 4
Library: 51
In Play:
-(U) Underground Sea (U/B dual land)
-(T) Island (Train's favorite card)
-(T) Grim Monolith (Doesn't untap as normal; T: 3; 4: Untap)
-(S, 3/3) Mistform Ultimus (is every creature type)
Graveyard...