In my latest 0.8 trunk run, i had lots of fun with a vampire necromancer, purely using necromancy spells.
I had reached the point i could obtain the necronomicon, that i selected as my vampire was not built toward close combat, and as i just found a ring of wizardry (that increase your spell mastery), i learned Haunt from it and thanks to the wizardry ring i could cast it very reliably.
Always trying to get at least 4 large abomination (thanks to the Twisted Resurrection spell and Kikku "Send corpses" ability that was coming in handy to rebuild some large abomination when they were destroyed), i was very happy of that character.
And to get more "meat" shield, the Animate Undead to get fresh zombies was very good.
And the Recall Undead to get back next to me my slower undead hordes was just perfect.
At some point i found the Vault branch and decided to explore the 3 first floors to get more experience.
In the 2nd floor of Vault i met an army of Orcs warrior and Orcs wizards, with an Orc Knight.
And behind them was Saint Rokka.
As i was at +/- 80 hit point, i could easily use Pain without worrying about my health too, and it's always efficient at that point of the game, in combination to Vampiric Draining if things got too personnal.
My zombie and large abomination horde found a good challenge there.
I already faced Saint Rokka with various kind of characters, i know that he can easily "Smite" you to death from afar by repeating it several time if you're not using a health based character, and i know that he can tear your character apart in close combat when you're not very high level.
So i used 2 time Haunt on him, to keep him busy.
But it created a big amount of spectral troops, and Saint Rokka was broken in multiple parts in only a few turns, it's always very rewarding to destroy that unique that has always given you a hard time.
And the remaining of the Orc army was unable to deal with the remaining spectres and my undead horde that were surrounding and overpowering them.
On the same floor, there was Mara, another very annoying unique, but as my vampire is very stealthy, Mara was sleeping.
He never knew what was coming to him when he was assaulted by a bunch of spectral creatures, he tried to blink away, only to land in the middle of my large abomination troops.
Mara never stood a chance.
It reminds me of so much of my character deaths, when trying to teleport away, all i did was landing in worse situation
Good that sometime it happens to those damned monsters.
So confidence was building up, something very bad in Crawl as it tends to make you forget that random generation can kill your character very easily.
My vampire and its army while exploring the 3rd floor were finished with a fight with several centaur warriors, those always very annoying missiles users that can fill you in arrows before you even understand what is happening.
So i was not anymore at full health, but i was + /- at 70 health, more than 3/4 of my total hit points, so i didn't bothered with resting or use potions as i could always need them later after all.
And while exploring the surrounding at some point what did i saw appearing in range : Xtahua.
Xtahua is on my list of the uniques i hate the most, for a good reason, each time i met it i was always using a character that had never found any kind of fire protection item.
And when you don't have such thing and meet Xtahua, you understand that Crawl wants to kill your character.
Xtahua was fully awake, unlike most of the monster i was going around thanks to my high stealth. That's another hint that Crawl do not want your character to go further.
Result for my 70 health character in the turn following my attempt at retreating to a nearby corner :
Korz the Reanimator (level 15, -1/93 HPs)
Began as a Vampire Necromancer on Dec 28, 2010.
Was a High Priest of Kikubaaqudgha.
Killed from afar by Xtahua (71 damage)
... with a blast of flame
Xtahua is now higher than anything else on my "must kill that damned thing" list