Should I have survived this quest Soloing?

[DYWYPI]

Yes, you should have been practising trying to using Bluff to separate individual targets from a pack of mobs when you were at a much lower level. You can hide behind objects or around a corner and still pull a single monster - as you've found out.

Hirelings can be Aggravation Magnets; especially if they have magical auras or guard effects surrounding them.

The other peculiar monster behaviour - to be aware of with stealth play - is mostly dungeon design or the current illogical "(mis)behaviour" of some of the monsters. That can easily cause illogical "chain-reaction aggravation", and so forth with regards to a Character in Sneak, etc.

Refer to the following thread: Question for the Devs: Why isn't Stealth Supported in Reaper?. That thread covers similar experiences, i.e. the successfully Sneaking Rogue won't be high on a monster 'Hate list' but gets illogical "chain-reaction aggravation", in some cases.

[...] Turns out Red Eyes can also still be assassinated. Aaaannnd, you can sometimes assassinate and not trigger the dummy standing right next to them. [...] I can assassinate hedges ...

You don't typically need to wake-up an inactivate mob first; just hit Assassinate when you are within kissing-range, that will be enough to activate, and 1-hit slay it.

I can think of several reasons why the DDO Developers' deliberately decided to spoil Assassinate with [U40.2].

The Sneak [button] now seems to be mostly just cosmetic with regards to Assassinate. Because you can stroll up to your amoeboid Ooze opponent (that has no vitals and already can sense you). Aggravate it; get it swinging wildly at you; begin using /dance to annoy it more... Tell it a joke about /death count, ask it "Do you come here often?" ...

Then simply Click Sneak, it will likely miss you, and then hit Assassinate resulting in; a pretty much dead Ooze!

[adamkatt]

Tower of Frost can get wicked. At that level, using a strong healing hire like Larafay can make a big difference.

Unless youre holding her back most of the time lara is like a machine gun, she never stop casting offensive spells.. she is the best at running out of sp.

[Bjond]

Unless youre holding her back most of the time lara is like a machine gun, she never stop casting offensive spells.. she is the best at running out of sp.

"Bombs away Larafay!"

She's great with a T5 spellsinger, but even that's not enough to keep her SP full. If you can manage to shrine often enough, she actually does enough DPS+CC to make a serious difference in the healing you might need. She's just as good as other healer hires in that respect, though; ie. she won't cast a heal without first casting some kind of DPS.

[Tilomere]

Divine healing + divine might with some healing skill/charisma is the end all, be all of new player learning DDO melee.

Should you have survived a level 15 hard fight with level 1 healing potions? No, probably not.