Long and arduous ascent of a remote and rarely climbed mountain.
It is technically an easy scramble (Class II terrain) once you are above the treeline, and views from the top are excellent. However, a heinous bushwhack from Mystic Pass Trail turnoff to the treeline makes it a very strenuous climb. The access drainage is a big mess filled with avalanche debris, broken timber and nasty bush. Once past this section, the ascent is lovely and terrain beautiful.

Since there is almost no beta online, I'll provide a brief description:
1. Start from Johnson Canyon or Moose Meadows trailhead. Walk 8km to Larry's Camp (CG Jo9).
2. Cross the bridge and at the fork take trail to Mystic Pass. Walk approximately 1km until you reach a bridge.
3. At this point leave the Trail and follow either side of the Creek. Initially, it seems easier on the right (east side). Bushwhack your way for 6-7km along the drainage to a beautiful and austere valley above the treeline. Follow the valley to the obvious col. Bushwhack is brutal - it's better to not stick very close to the creek.
4. Follow the valley 1.5-2km to the obvious col. From the col, Block Mountain shows her pretty face. The ascent route is obvious although foreshortened. It's still 2.5km away. Drop 100m and follow glacier moraine or snow to the base of the mountain. From there almost any ascent line will work. The slope is steep but the scree is not too bad.
5. Arrive at the summit at 2950m and 20km from the parking lot.

It took me 17 hours with 40 minute summit stop. I was very exhausted by brutal bushwhack on a hot summer day and on the way up stayed close to the drainage. On the way back, I stayed a couple hundred meters away from the creek on the east side and the bushwhack wasn't so bad. I think fit people who find a better way around the creek can do this peak in 14 hours. It's still a very long day.