Just came back to the game after a long break, and I finally managed to rainbow all the dungeons.
I waited to unlock Goatperson until I finished all the other classes and badges. I was able to beat most dungeons in 1-2 tries. Most of my trouble came from Shifting Passages (which required me to change my strategy to start prepping Yendor instead of Dragon Shield) and Vicious Gaan-Telet. I got VGT in about 5-6 attempts. Most of my trouble came from bad god luck or getting poisoned/mana burned too many times.
On my winning attempt, I got great luck with an early Binlor+Pactmaker, Ritual Scroll, and resists boosts from Patches. I had mid-50s in both resists going into the second tower level. However, the map didn't have a Soul Orb, and I slowly ran out of ways to remove my manaburn. It came down to the very last enemy manaburning me on his last hit. Thankfully, I had enough conversions left to remove all of Horatio's resists with BYSSEPS and got a lucky 50% Last Chance. I managed to kill Horatio with what was probably my last hit. I had a small amount of blackspace that may have given me one more.
Rat VGT was a lot easier than I thought it would be. I got it on my second try (scumming for early Pactmaker). Really happy I got it fast, because I ended up spending 8k gold trying to get Pactmaker to show up.