East pather (and all trash in east) can be level 50-54 iirc. A level 50 wouldn't be too hard to lock down at 55, but a 54 would be brutal.
Misc comments: if you get a magic dot buried behind buffs, click off buffs rather than dispelling all of them. Don't finish off a skeleton mob when you need to med up after the fight; keep him dazzled or rooted and ToT him. You can invis down to the orb room and safely drop invis and mem new spells and stuff in the corner of that room that doesn't have a scorp spawn in it. You say you learned a lesson of playing it safe, but you still aren't stocking peridots and backup charisma gear (AT LEAST get dots in there!) for CRs! That's not playing it safe!
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Misc question: mezzes can break before their full duration now? Are you sure a pet isn't hitting stuff?
You can totally do north at 56. It takes some time/deaths to figure out the pathers and timings and such, but it really is as safe a place as any once you know it, especially since the odds of you ever running into another player in there are slim to none (or if you do see someone else in the zone, you'll be able to see them coming before they get to you with gnoming through the walls or bind sight or something). North starts dropping loot that sells pretty nicely on red, too, since there are some resist pieces besides the wis belt and monk club (and more 51-54 spells) and stuff.