Ultraxion 10 - If you can end the fight by the 5 minute mark, it's much easier. That's why people often recommend 2-healing it. I joined another guild's pug this weekend that hadn't beaten the fight before, and they just didn't have the dps to finish before the 5-minute mark even with a healer switching. Reason being: they had a mage doing 16k dps, and their healers were poor in their dps off-specs as well..
I think the chances of successfully 2-healing past the 5-minute are slim, so I'd say stick with 3 healers unless you've got good dps (and your healer wouldn't be useless if they switched to dps). Pretty easy to do the math based on what % he is at 5-minutes, and how much dps your healer can put out. We did eventually kill him, getting fairly close to the enrage timer but being able to brute force the healing with 3.
As for blackhorn, we had a lot of people who sucked at dodging shockwave. Our solution was to not dps Blackhorn at all until Gariona had left. This way, blackhorn does not gain vengeance stacks, so shockwave and shout will not be lethal if they do hit someone. Once gariona has left and you're not getting voids anymore, people are usually a bit better at dodging shockwaves. The downside to this obviously is that you've got melee dps (like my rogue) doing absolutely nothing for 30-40 seconds. There is no enrage timer on the fight, so it's only an annoyance and not a liability.
