Ascension is unlocked lvl22, i tried it lvl 25 and succeeded it (monk, v0.2 HC standard league, no buy). I'm casual player (not played endgame more than 3 hours)
It was the first challenge proposed in 0.1, which as for all the game, can be solved with just... better gear.
Not all that is proposed can be done fingers in the nose without gear. That is what also makes great the reroll experience where you can 'feel' the difference of your smurf equipement to levelup faster.
I'm glad they kept their vision on slow combo based combat. Otherwise they would throw under the bus all the nice animation and different attack pattern they developped on each monster. I hoped they would reduce the monster move speed and make them a bit more deadly so that play positionning matter more. Some mobs already play thar well : the sorceress with the read area marker ib the first area, the knight with the shield sending a green projectile on hit in the mausoleums..
0.2 launch was rockandroll on the technical side. I couldn't play on AMD gpu until 6hours after launch. This hurted their reputation, despite technically being fine. (Firsr cohort reported issue, fix deployed super fast)