Maybe some/all of this has been climbed before, maybe not. We didn't see any evidence on route, but aside from a few trundled holds, we didn't leave any either.
Pitch 1. From the large ledge at the base of the buttress, climb intermittent cracks up and right to the large, RFC. Ascend the steep, RFC via big holds, exiting left at the top to a good belay stance. (5.7)
Pitch 2. From the belay ascend up and left via ledges and short corners until it is possible to move back right to the prow on good, but slightly runout holds. Belay on the large ledge directly below the obvious roof.
Pitch 3. Traverse to the right side of the ledge and ascend the thin crack to just below the roof. Place good gear and move right on an exciting, undercling traverse to gain an obvious, right-facing corner. Ascend the corner. We belayed below a short 5' headwall due to rope drag. (Awesome 5.9)
Pitch 4. Climb the short challenging headwall, then ascend easier terrain to the top of the buttress. (5.8)
Climb ascends obvious buttress.
We descended by hiking west until past the true summit of Otis Peak, then descending the scree gully to Andrew's Glacier/Tarn.
Standard rack to 4". #4 is probably optional.