Greyman, Draenor, Pandaren, 535ilvl, 3/1/3/1/2/3 BM ( Spec made specially for this fight )
Lord Rhyolith - Firelands - Solo
Edit - Laundry
Decided to do this fight on HC after killing it on normal some months ago (for that I went as SV but I thought about going BM because of extra healing from pet which might be needed if you get too many stacks of debuff ).
Glyph of Animal Bonding - All healing done to you+pet increased by 10%
Glyph of Mending - Increase the healing done by Mend Pet by 60%
Glyph of Liberation - Healed for 5% of total health when you Disengage.
Main problem is that after the nerfs, the boss moves very slow. If you get bad RNG on the "active volcanoes" you'll have problems with stacking debuffs (+% fire damage taken) and you won't be able to drop them by destroying the volcano because it's too far away. Also, if you don't clear your path in such way to anticipate the next active one, I'd suggest Dismiss + Feign Death, start from scratch.
Pet doesn't really need much healing unless the "Spark of Rhyolith" is alive too much or in the last phase while tanking the boss.
Stay under the feet you want to damage for driving while MD-ing the adds on the pet. Time your deterrence for maximum incoming damage (i.e. stacks/adds + stomp and all possible combinations).