Last night, I ran with a friend's guild on normal Mannoroth. I started with them playing with them as Elkagorasa doing dps, but he was ranking 9:11, even below both tanks.. (/sigh). Blame it on my average gear score being 10-15 points lower than everyone else.
Half way through the night, I swapped to Eride and healed the fight a few times. We still never won the fight, best was 9% down before wipe.
To help me out, I have collected a few videos that give some strategies.
Curse of doom, take damage and the curse will disappear. Run to pool in center.
DPS/Healer - Don't stand in front of boss.
Phase 4 - # of people in 'circle' [soaking damage during gaze] determine how big the pond will be.
Save lust cooldowns at 35%
FatBoss changes the strategy where the raid group stands at the pillar and tanks are in middle. This way you don't need to manage the 'gaze'. People are already grouped together and simply grouped together.
Last video is from a Discipline Priest POV. It's nice because she also gives actual damage numbers for each boss activity, then steps through to show how her guild completed the phases.