Riding Out the Swarm

The Heroic Anub'arak encounter places great strain on a 10-man raid attempting it. Teams with a relatively weak dps team may choose to bring two healers into it, placing a great burden on the healing team during Phase 3.

Phase 3 is notorious for Leeching Swarm that Anub'arak keeps up during this time. This is coupled with a heavily ticking Penetrating Cold debuff cast on three random players. Due to high-hitting melee attacks and Freezing Slash, one healer usually must focus 100% on healing the main tank, leaving the other healer handling the raid and the offtank. That raid healer has a hard job, though a few tips and tricks may make it much easier.

It's not as bad as it seems

Do not worry, this oversized bug can be squished.

This encounter is unique in that it goes against the basic healer instinct of keeping as many players up as possible. Unless the main tank healer is very able, they should devote all of their attention on the main tank. Were they to switch targets at a time when the main tank receives consecutive hits, the main tank may end up dying. It becomes very important that the main tank healer stay 100% on the main tank. If they are worrying about the state of the rest of the raid, they might be overestimating the damage the raid is receiving...

It is easy to overestimate the damage that Leeching Swarm does, and the raid healer might panic accordingly. However, under close inspection of the debuff, a fixed percentage of current health is leeched, down to a minimum of 250 health. That means that a player receives less damage the lower their health is (in an exponentially decaying way). To think that a fixed percentage of total health is leeched is to overestimate the damage. To reasonably satisfy the trade-off between minimising the amount by which Anub'arak heals and maximising the safety margin from death, a rule of thumb of 40% of total health is usually appropriate.

Watch out for Penetrating Cold
Although Leeching Swarm damage is exponentially decaying, Penetrating Cold damage is constant. It becomes important that the raid healer maintains a healthy safety margin for each player's health. The raid healer needs to quickly spot those with the debuff and focus some healing on them. Under the default Blizzard UI, the icon of the debuff appears next to the health bars of the players affected by it; it shares the same icon as Frozen Orb. Custom UIs may be able to indicate affected players as well by highlighting the respective health bars or declaring it in text.

Don't forget the offtank!
The offtank takes the same damage from Nerubian Burrowers, if not more, than any player does from Penetrating Cold. They should be given the same amount of attention. Since they will always be taking damage from the add (unlike any player, since the debuff only lasts 18 seconds), it may help to place the offtank on /focus. This removes them from the already difficult juggling between those affected by Penetrating Cold. Interface Options allow directing spells towards the Focus target by holding down the Ctrl, Alt or Shift keys, making click-casting healing much easier; however, since Alt is already used for directing spells to the self, this particular option is better avoided.

It's a team effort, after all
There are many examples of things the rest of the raid can do to help the raid healer with their difficult endeavour:

• A shaman's Bloodlust/Heroism can be activated during this phase to get the raid through as quickly as possible.
• A Shadow priest with Vampiric Embrace can lighten the healing load considerably in this AoE-intensive period.
• A paladin activating Divine Sacrifice and Divine Shield simultaneously will mitigate a hefty chunk of that damage.
• Leeching Swarm is resistible, so a hunter's Aspect of the Wild or a shaman's Nature Resistance Totem (but not both) will help.
• This is a good time to personally use Healthstones, healing potions or frost protection potions (if affected by Penetrating Cold)!

Keep at it!
Any shortfall in ability can only can only be made up for with practice. If you are a raid healer faced with this problem, good luck!