The Tavern

I am currently at the vaults entrance, wielding a +9 bardiche of protection. I have the swamp rune. I have a +8 chain mail with Nr+. My skills are quite high. Fighting at 18, polearms at 21, dodging at 16, invocations at 7.
These are my main skills.
What should I do now?

Have you cleared Orc? Do you have poison resistance? If yes to both, go to Snake/Spider, whichever you have.

Cleared orc. Came to me as a surprise when I one shot killed Saint Roka. I don't have poison resistance sadly. But I do have a few rings that aren't identified. I have a +3 swamp dragon armour tho. Is my weapon good for the deeper dungeon? TSO is proving to be a great pick.
I am afraid of the snake pit because of the constriction.
EDIT: Is it unusual that shoals didn't generate?

Me? You mean Mf (Merfolk)? TSO is a weird choice early, but you've made it this far.

The rN+ is irrelevant since you are of TSO (Passive rN+++ is one of your god's gifts). Chain mail isn't heavy; but it's heavily enough you might want to turn on Armour to get it like 8-10ish.

What's your other lair branch? Spider or Snake? Do you have any ranged attacks? Javelins, etc? Are you completely magicless or are you using boosts? [You probably should post the whole chardump (hit Shift-3 [#] to get the game to print it); then put it in a code box in your original post so people know all about your character instead of 3 sentences]. I do recommend using Javelins/Throwing on a Mf to have some ranged attacks.

But; going on that bit. TSO is usually an extended god (his powers work better on the demons of the later branches than the natural monsters of the earlier ones; but those branches are generally deadlier; so perhaps not a good idea for younger players. As myself on that character; I'd probably do the remaining Lair branch (Spider/Snake) with the Bardiche as is [maybe not if you have no clarity or rPois though]; then go ahead and have TSO bless it [change brand to Holy Wrath] and get one of the extended runes (Abyss, probably) as my third. You'll want some stealth before doing Abyss; as discretion is the better part of valour there. [Constantly shifts, constant spawns; you don't want to fight everything.] Vaults 1-4 probably aren't TOO bad [if you have a ranged option]; but Vaults: 5 is one of the hardest floors in the game, don't do it yet.

Sorry I write a lot.

EDIT:
You posted while I was writing this.

Switch to the +3 Swamp Dragon and do Snake; you'll be fine. Train stealth and armour a bit while you are there. I'd recommend doing Abyss as your third (and potentially last if you want an 'easier' win) rune after. All other options are harder that that one for that character.

If you have remove curse scrolls, identify those rings by wearing them. A +9 bardiche is an end game weapon. Rebrand it when you find the appropriate scroll. Snake can be done without rP+, but you can try how it feels with the swamp dragon armour. Constriction is not such a big deal, just try to fight in corridors so that no one else but the constrictor gets to you. (Well, except monsters with polearms or sharpshooters with Portal Projectile...)

You always get either Swamp or Shoals, and either Snake or Spider.

Edit: I understand bcadren's point of view, but personally I would never recommend Abyss as third rune for a (presumably) inexperienced player. It's such a different place...

If I rebrand my bardiche will I keep the +9?
Thanks for the tips. Will post a full dump tomorrow.

Yes.

I have the spider branch available.
Also I don't have any ranged weapons. The bardiche has a two tile range to it if it helps.

Posting a character dump would help to give advice.

While in game press #. Then put the content of the file in code tags.

You don't necessarily need a ranged weapon. Often stones are enough to pull one enemy at a time from range. But let's see what your character actually looks like.

Will post one in a few hours.