A couple of notes about retreating:
When using RETREAT, one thing that often hinders people is armor. I know it may be counter-intuitive, but if you try taking off a big piece of armor or two first, you may suddenly find yourself able to get out.
Also, balance seems to play a role. If you CIRCLE a few times (or maybe BOB?), you may regain some balance and find yourself able to get out.
Further, as mentioned, you can use FLEE to get out of combat too. Don't be alarmed the first time you try it, as it works a little differently. It will take a chunk of your fatigue, then wait ~10 seconds before it tries to extract you -- you can still be hit during this time and the flee might even fail because of it! But it's better than being totally stuck. Use FLEE <direction> to go in a direction (usually best). You can also FLEE in a direction that doesn't exist to just go to missile range, e.g. FLEE OUT in a room without "out."
Finally, you may also wish to make some use of stealth. For example, you could hide and eat some remedies quickly, or even cast some healing spells (though you'll have to re-hide). It can give you a chance to catch your breath and figure out which of the above you'd like to try. Keep in mind that FLEE is probably best against a creature that vastly outclasses you, like that invasion guardian.
Oh, and check out that divine charm, and try to build up to ~10 favors to give yourself some leeway!
- Navesi
