2nd

You can approach Deer Ridge Buttress from either the north or the south side. For the north side, just slog directly up the slope, with no trail. For the south side, hike the Deer Mountian Trail (access inside RMNP) to the end of the northernmost switchback, and then cut off the trail and hike up the ridge until reaching a gully just west of Deer Ridge Buttress. Rack up, leave your packs, and descend the gully to the base of the wall. Both approaches take roughly 1 hour to the base of the buttress.

We chose to approach from the north side to avoid having to deal with the RMNP entrance. This way is a bit of a hoof, but hey it's good exercise and the climb is fun. 

5.8-5.10

Several options

From the base of the main wall, follow one of several lines of weakness to the large ledge ("Stagway") below Nun's Buttress. There are several options ranging from 5.8-5.10. It is also possible to scramble up and left to get to Stagway and the base of Nun's Buttress.

I have climbed three different options to Stagway, shown below.

Option 1

Option 2

Option 3

5.8

Nun's Buttress

Gain a beautiful double crack system with a hand traverse from the left. Follow the right branch for a long pitch to a ledge at the base of a very prominent, jutting dihedral. This is an awesome 5.8 pitch.

5.7 or 5.8

Nun's Buttress

Climb a crack on the right wall of the jutting dihedral or do an easier line on the left. Belay when convenient.

5.7

Nun's Buttress

Head up moderate slabby terrain to the top.

3rd

We descended by scrambling off the top of the buttress to the west. Apparently you can also descend to the east, which may require a rappel off a tree at some point. The descent is a bit loose and tedious.

2nd

You can approach Deer Ridge Buttress from either the north or the south side. For the north side, just slog directly up the slope, with no trail. For the south side, hike the Deer Mountian Trail (access inside RMNP) to the end of the northernmost switchback, and then cut off the trail and hike up the ridge until reaching a gully just west of Deer Ridge Buttress. Rack up, leave your packs, and descend the gully to the base of the wall. Both approaches take roughly 1 hour to the base of the buttress.

We had approached via the north side the last time we had climbed the buttress, so this time we chose to approach from the Deer Mountian Trail. We thought this way was much more pleasant, and it was nice to have our packs at the top and just hike out at the end of the climb. 

5.8 or 5.9

Twin cracks about 30' left of a chimney, 30' right of a blocky, low angle crack. Follow twin cracks up for roughly 80' and then step left into the upper reaches of the aforementioned chimney. Follow this right into the low angle, broken terrain below a white slot. With a 70m rope, this could be continued to a spike belay below the crux slot, 180-200', 5.8/9.

(Pitch description by Andy Hansen on mountainproject.)

Here the route description in the Rossiter and Gillette guidebooks differ from what Andy described. They describe laybacking (5.9) a flake just left of a 6-inch wide slot and ending at the same location. This may be a bit to the right of what we climbed.

5.4

Climb blocky terrain to a large spike below the white slot, 50', 5.4.

(Pitch description by Andy Hansen on mountainproject. This pitch seems to fit those described in both the Gillette & Rossiter guidebooks.)

5.10b/c

Move up into the looming slot easily. Out right you'll notice an incipient crack system, but stay the course in the slot placing finger-sized cams/nuts. The slot begins to widen. Turn around, and use jugs/flakes in the other wall. Keep laybacking until a fortuitous foothold presents itself out right. Keep laybacking up through the roof, and latch a jug. A strenuous pitch but not technically difficult. Step left and belay at a semi-hanging stance, 90', 5.10b/c.

(Pitch description by Andy Hansen on mountainproject. This pitch seems to fit those described in both the Gillette & Rossiter guidebooks. It is also possible to climb a wider crack out left, but this would requie a few #5 to #5 sized cams.)

5.9

Hand traverse awkwardly to the left and step up into a thin hands crack. Follow this for 90', and then continue up slightly left into a roof-let in easier, slightly lower angle terrain. Semi-hanging stance in a finger crack/large rock spike. 150', 5.9.

(Pitch description by Andy Hansen on mountainproject.)

Here the route description in the Rossiter and Gillette guidebooks differ from what Andy described. They describe stepping back right, climbing a wide 5.8 crack, and then climbing a finger crack in a long, clean, right-facing dihedral which is the same as the last pitch of Pathfinder.
We climbed Andy's version, which was good but we will have to someday go back and climb the other last pitch option to compare. Via Andy's version, we belayed about 70 feet up this pitch to avoid rope drag, and then combined the last half of the pitch with the final pitch to the top.

5.8

A short pitch may be necessary to complete the climb.

Enjoy the view. Collect your packs (if you approached from the trail and left them up here) and hike out, enjoying more views.