We actually accidentally climbed this to short-cut from "Zacheus, 10d," and "DC Boy, 11d," on the Lower East Face of the Fourth to "Death and Transfiguration" on Green Mountain Pinnacle. The best Flatiron book describing the area is the one by Jason Hass, 2009.
Approach same as Royal Arch, before Royal Arch cut up between the Fourth/Tangen Towers/Fifth. After finding Routes "Zacheus, 10d," and "DC Boy, 11d," on the Lower East Face of the Fourth, continue up into the Gully above. The route tops out Mid-West Face of Fourth, and below Last FlatIronette.
-Few pins on 1st pitch (probably 40 years old)
(Both pitches are run-out.)
Looking down first pitch.
Looking down second pitch.