Orc Transmuter was responsible for that damage output, Glowing Guardian and Alchemist Scroll in conjunction wer responsible for those hit points. All three of those things have since been nerfed, for reasons that should be pretty obvious. Glowing Guardian, Orc, and Transmuter were completely overhauled, while Alchemist Scroll just took a flat nerf.
Orcs used to have a scaling conversion bonus. The first threshold gave +1 base attack, the second threshold gave +2, the third +3, and so on and so forth. The problem was that this quadratic scaling became utterly broken if you exceeded the game's presumption that there's only about 800 CP available. The Transmuter (I think this was the third or fourth iteration? That class was reworked so many times...) had the ability to magnify CP gains, more than doubling what you could expect over the course of the run. With 1600 or more CP available, you could easily triple your base attack as a 10th level character, with the obvious game-breaking implications.
Glowing Guardian Absolution also worked differently back then. The rate was the same - 4 HP per monster - but there were no beads and it was a single-use boon rather than a repeatable one. Instead of randomly removing a single monster, every monster that was lower-level than you got converted to HP. This was incredibly double-edged, as you completely cleared the board of popcorn in the process, but the hit point gain was out of this world. The Alchemist's Scroll had a higher hit point bonus and didn't have the "once per level" limit, so it could also contribute way more hit points than it can now.
This was pretty typical of the beta, with the "broken strategy de jour" making headlines and everyone rushing out to abuse it before the devs gave it the smackdown.