Half-dragon dire-corby from pathfinder. Works out to cr4 if i remember right. Took some levels of summoner and barbarian. Well ok by the end of it i was level 25 but alot of that was dragon deciple cause breath weapon. Anyway it was such a powerfull race and summoner build that it took down creatures and players 20 levels above it. By the end of the campaign he also had 5 breath weapons because dm was giving out special powers amd mythic ranks like candy on Halloween. But heres the thing, my level 16 pathfinder half dragon dire corby killed a cr 35 demi god from 3rd edition dnd that the dm threw in specifically to kill me after i 1 hit a cr 19 pathfinder creature. Seriously cant stop this beast