BigWigs was working for this encounter, though I used DBM for Magmaw. YMMV as they say.
If you want a complete walkthrough, go check out tankspot or bosskillers. Here's the Crib Sheet version, with an emphasis for healers. We used a Holy Paladin, Resto-Shaman, and Druid for this fight. It's more about control and staying alive than raw DPS output.
Shared 'lookout' abilities
Each 'Tron' will have an ability that focuses a single party member, an AoE, and a shield that they put up to force a target change. Your tanks will have to hold off a few seconds during a target switch, otherwise they'll kill themselves. This will reduce the amount of self healing they can perform, so keep a weather eye out.
AoE - Standard fire - shoots all across the room, no range. We used Aura Mastery and and Divine Gaurdian to help soften this.
Single Target - At least once per 'active' time, Magmatron will announce that he is "Aquireing Target x". This person will need to get clear of the raid (A big, giant, MASSIVE red beam will be on them before the fire starts) and will need to have dedicated healing or use some CDs to get through this focus fire.
Electron (guess what power he uses?)
AoE - Similar to Freya, one player will get a static field placed on them (Lightning Conductor). Stay away from this player and there's nothing to worry about. They don't take damage, just those that they get near.
Single Target - Technically this could be an AoE, since it's a chain lightning, but as long as you're more than 8yds apart, this will only hit one person.
Arcanatron (you'll never get this one - come on, guess!)
AoE - Power Genorator. This is similar to the Iron Council, a pool will appear on the ground that you need to move the boss out of ASAP. Standing in the pool provides a huge chunk of mana return, as well as significantly increasing the DPS of your ranged. Use at your own risk, depending on which other Tron is up at the moment.
Single Target - The only interruptable ability, this will do a ton of damage (about 60k) to one player, it should be interuupted whenever possible. It is worth the DPS loss to have someone sit on this, even when this Tron is shielded (just don't DPS while waiting to interrupt).
AoE - Chemical Bomb gets shot at a random raid member, and it makes a big cloud on the ground. Drag the Tron into this to get a big damage boost - don't stand in it.
Single Target - Poison Protocol will target 3 members (in 10m, unsure about 25m) with small adds that will explode on contact killing their target, and leaving a nasty pile of goo on the ground. We put all DPS on them, since they can target anyone (including the tank on the other Tron), and they seem to have an affinity for healers.
The fight in a nutshell
Pull the active Tron. After approx 60 sec, the 2nd tank will pick up the new Tron, and DPS switches. Handle any AoE nonsense, and repeat until dead.
- If you get Toxitron first, have the raid stack up together near him - until the first cloud comes out. This will let you position him in the cloud early, and is a great time for an early Bloodlust. Remember to spread out to avoid the little slimes though.
- Arcanatron and Electron pose an interesting challenge. You'll want to stay spread out to minimize damage from the Chain Lightning, but still get the mana regen and ranged DPS boost from the Arcane pool. Choose wisely.
- The fight is long, so pace yourself.
- Don't hit a shielded add. If someone happens to hit Toxitron's shield, you can dispell the poison.
Good luck and have fun with him. Hopefully I'll have a new Crib Sheet for something other than Magmaw later this week.