I recently completed the OC solo with a cleric, finishing at level 17.
I have finished the game before many years ago as a sorcerer and while that was rather easy, it was not nearly so as this.
I recall having level 25 characters in HOU that were not as powerful as my level 17 cleric.
As long as no one dispelled my buffs (and that hardly ever happened), the character was almost unstoppable - the buffing spells and good gear gave me incredible saving throws (something like 35 25 32 at lvl17), good stats, insane attack power with Divine power (more than that of a warrior because of how extra attacks use max to hit values), stoneskin, rather high armor, full heals and many smaller heals, harm (wow, crazy spell), demon summoning etc.
Now I am sure this is not the most powerful character that could exist and my intention here is not to brag
But I am curious if anyone has suggestions for a power class that breezes through the game from levels 1 onwards (as my priest did) and remains powerful and ideally becomes a powerhouse after it gets to higher levels.
I would like to play the OC again and transfer my char to HOU and get to the highest possible level I can, playing solo.