Encore is by far the best staff in the game right now stat wise.. well, as long as you don't care about aesthetics. If you're like me and do care about looks however, then I'll list the materials I'd recommend using for either a Staff of Corruption or Archon Fire Staff. (If you want a WoL build as well, let me know and I can post one, but honestly unless you don't have access to Encore, and you REALLY want Dorian to crit a lot without having to equip him with Mask of the Grand Duchess, it's not that great imo.)
- Staff: Staff of Corruption
- Materials: Dragon Bone (24 metal slot), Dragon Webbing (20 cloth slot), Great Bear Hide (6 leather slot), Everite/Stormheart/IDB (12 metal slot)
- Masterwork: Fade-Touched Hardened Gurn Hide (30% damage bonus if not being hit for 5 seconds) - Recommend not using this for Dorian, AI gets hit a lot.
- Staff: Archon Fire Staff
- Materials: Dragon Bone (24 metal slot), Dragon Webbing (20 cloth slot), Great Bear Hide (6 leather slot), Infused Vyrantium Samite (12 cloth slot)
- Masterwork: See above
- Staff: Encore
- Materials: Dragon Bone (24 metal slot), Dragon Webbing (8 cloth slot), Dragon Webbing (8 cloth slot), Everite/Stormheart/IDB, (6 metal slot)
- Ranged Masterwork: Fade-Touched Hardened Gurn Hide (30% damage if not being hit for 5 seconds) - Again, not for Dorian.
- Melee Masterwork: Fade-Touched Bloodstone/Pyrophite (7.5% damage per enemy within 8 meters)
- Staff Grip: Hilted Staff Grip
- Materials: Great Bear Hide (8 leather slot), Plush Fustian Velvet (3 cloth slot)
- Staff Blade: Dragon Staff Blade
- Materials: Craggy Skin/Lurker Scales (6 leather slot), Everite/Stormheart/IDB (3 metal slot)
(For Dorian, I'd substitute the CS/LS in the 6 leather slot for GBH for more crit chance)
Anyway, sorry for the lengthy response. Pyromancer is one of my favourite builds and I got excited. I used it to solo nightmare pre trials (with Blackwall for tank support) and it was soooo much fun, so I may have gone a little bit overboard with my response. Hopefully you get some use out of my ramblings though. 
By the way, regarding DoT, pyromancers do have some nice DoT abilities it's true, but you'll get the most bang for your buck (especially on an inquisitor PM) if you build for high crit damage, accompanied by at least 30% crit chance. The reason for this is that while burning/spirit damage ticks away, you should also be focusing on slamming enemies with the initial hits from fire mine, energy barrage, immolate, and walking bomb. That's where the bulk of your damage will ultimately come from, and why you should focus on maximizing that with a decent amount of crit chance, as well as as much crit damage as you can muster. :3
And yes @ Bigdawg13, the explosion from WB can crit.