Heroic: Lord Rhyolith

Differences in Heroic:

Everytime an active volcano is stomped, 10 obsidium adds spawn from outside the platform and slowly converge onto him. Each obsidium add that reaches him gives him back one stack of armor.

Much higher damage from active volcanoes staying up for too long. Stomp is much more deadly.

The biggest kicker is that after being active for 5 minutes, he will start to gain the "Superheated" buff. This is a stackable buff that increases his fire damage by 10% per stack, starting with one stack and gaining a new stack every 10 seconds. Thus this makes the fight a soft enrage.

Phase two, he also has 3 fire beams circling the platform. They can be avoided pretty easily but they can move pretty fast. They are very similar to Yogg beams, you need to avoid them.

Tactics:
The superheated buff is the big kicker here. If the boss has too many of this buff heading into P2, it will be a wipe because the damage will be way too high.

First off, split up your DPS accordingly. You need to target the obsidiums as they spawn along with the other adds. Fragments can and should be gathered up and AoEd over as many obsidiums as possible. Try to prevent obsidiums from reaching the boss, but in reality (at least in 10m), there's no way you can kill them all. knockbacks also work on them.

At some point in the fight, you pretty much need to drop what you are doing and focus on the boss, pushing him to Phase 2 before Superheated. This should happen around 20-30 stacks of armor (hopefully lower), and 50-60% health (hopefully lower). All DPS focus on one leg, tank any leftover sparks, and just burn burn burn to Phase 2. You need to find a good time of when actually to burn and it'll depend on your raid. Some tips, you need to make sure the fragments have recently died, an active volcano has recently been stomped, and you need to do it sooner rather than later.

Assuming all goes well (this is assuming good Volcano RNG, which always won't happen), he'll push to P2. Bloodlust if you haven't already, and go nuts with damage reducing cooldown. Use immunities during stomps. Put damage reducing abilities on the tank (he'll take a crapload of damage). Dodge beams. Healthstones. DPS potions. Live live live, and burn.

Good luck to you guys, this fight is frustrating mostly because of the bad RNG that can sometimes happen with Volcanoes, if one is too far away, or if you accidently miss one barely when turning, it's usually a wipe because having two active volcanoes up at the same time = too much damage and you're wasting too much time with extra armor stacks up meaning you'll reach Superheated sooner rather than later

recent hotfix changed a few things: Lord Rhyolith - The explosion damage radius of each Magma Meteor just before Lord Rhyolith should now more closely match their spell effect visuals. Volcanoes should no longer emit plumes of smoke while they are dormant. - Concussive Stomp should no longer knock nearby players back. - Magma Flow lines are now 30 yards long, down from 40 yards. - Rhyolith now activates volcanoes less often on normal difficulty. - Stepping on an active volcano now removes 16 stacks of armor, up from 10. the above guide is great, and still usefull. and the

If you are having issues with Not an Ambi-Turner or Heroic Lord Rhyolith I made a simple guide for it.

Simple WoW Guide - Not an Ambi-Turner Solo lvl 100 (Heroic)
https://www.youtube.com/watch?v=gZTUetjqBv4