Training Reference For All Magicians

best place for a level 33 cleric to train in ossyria?

Monster Carnival. I really don't think any of the Orbis or El Nath monsters are good for 3x, except maybe junior kitties. Monster Carnival is free experience because you don't need potions, and lots of people will invite you just because you're a Cleric.

Whenever you can kill the kitties easily, I'd suggest training on the ones that potentially drop the Flaming Feather. You'll need one for a quest at level 45 (Manji's Ragged Gladius) and if you get an extra one they sell quite fast. Jr. Lioners also drop mithril ore, which is another good money-maker these days due to Horntail runners always needing plates.