Wow. Going into Skellington at 79 with no IC without max dex(Okay, maybe I did went there at level 72 as a Priest without any fancy gears and a retarded Magnus Exorcismus, so hmm - I guess it is okay).

Umm... I suppose hearing what is one geared with would tell everyone much more of your capabilities of training in Skellington. If one is going in there with no IC, I suppose that you might have several complements to ensure survivability there):
1. Good Defense Rate with proper cast speed or excellent maneuvering.
2. Proper flee amount with an uninterruptable cast.
3. Planning to go in there with a small/controlled mob.
4. Status armors with good/excellent defense rate.
5. A companion to shield one from most attacks or give support.
6. Some crazy new revolutionary idea I do not know of.
Hmm... a bit of extra clarification is required. ._.
Max dex, low int is dangerous at that level(But I suppose you have a Kaho - so the impact is much, much less). But if you have a good defense rate and resistance or even a good cooldown, I suppose you could do that. Sanctuary would be a personal choice if you're going for IC, Safety Wall if you have proper cast speed and/or a status armor where Safety Wall is mainly a transition pathway for one to shoot in a cast, rather than damage resistance.