Hi guys!
This guide, I should preface, is usable by anyone with a fairly strong ranged attack (Nemesis Staff, for example) and any old ranged AoE, of any strength (from Freezing Rain to Fireball). Fireball like moves alone should suffice.
This guide talks about a fairly simple & easy leveling tactic that can be done as soon as you hit 20 in Striga Isle. I believe the tactic might work elsewhere (anywhere mobs are clustered around bombs, say Red River in the Hollows) but this is where I discovered it.
Upon entering Striga Isle, head north to a couple of huge boats with mobs all over them. You should see in this area groups of mobs, usually including 1-2 bosses, clustered around a bomb and an explosive.
First, you tag all the mobs by using the AoE. Then, hopefully before they kill you, you destroy the bomb. Note: MAKE SURE NOT TO TARGET THE EXPLOSIVE. Bombs have far fewer hitpoints than even a minion, while explosives are significantly harder to kill. What should happen is the bomb goes off...setting off the explosive...and killing all the mobs. Since you've tagged them all, you are now the proud owner of 4-600 XP or so. Quite a bit if you do this immediately at 20.
Well...that's about it. Be careful around Consiglieres, they have holds. And be ready to run like hell if you miss the bomb. But even with debt, this is a FAST way to level, at least for a little.