ToME: the Tales of Maj'Eyal

First time mage (PM) here. It seems I cant hit anything with staff, and attack value is 0, though I have some dex. Should I invest in combat accuracy, or the only way to get staff useful is to get staff combat skill from escort? How useful staff combat for mage anyway?

The staff improves your spellpower and other stats, which is mostly what it's for. It's not that useful as an actual weapon, but when you're a walking engine of destruction, like a good mage should be, you don't need an actual weapon.

Alchemists are the only class that's really designed to be awesome with staves, and their Channel Staff ability Always hits, so they don't have to worry about accuracy. Archmages normally just use staves for boosting their spellpower and resists and suchlike, unless they happen to get the staff combat tree from an Alchemist escort.

Staves are actually very good in combat as long as you only care about your magic stat. As staves damage scale with 100% magic, they can do some serious damage in a hurry, even though their base range damage is generally rather low. Keep in mind too, however, that staves can do elemental damage innately, and can even raise that damage innately [such as a Fiery staff that deals Fire damage].

Try using a staff with an AB some time to see what a staff REALLY can do.

However the base damage of high end staves is awful compared with other weapons, making them useless pretty quick. Any caster will struggle to hit with it due to low St and Dx, and will want to spend their generics elsewhere than the accuracy and staff combat talents.