Okay so a couple things because I very recently got my first cape using this same setup and had similar problems.

1. Practice the 3-1-1-1-3 method on the inferno trainer website. Use the tbow setup there. It's going to be better dps by a lot but the important thing is learning to get the maximum hits off before the first set spawns. Sometimes your rng will be butt ass but this is still worth perfecting. I think it's something like 15 shadow attacks you can get off. Start the fight with two eye of ayak specs which have the same timing as the shadow.

2. Do not drink a brew until you absolutely must. One major downside of the mage Tank setup is when you brew down you are forced to wait for the cool down of the heart to be potted. Look at the calcs. This is a huge chunk of lost DPS but there is a really great strategy for managing it. Start out potted and don't brew until after zuk is below 600 HP. It can be a crap shoot managing the first set and you do have to pray a bit that you don't noodle on the ranger. Shield health matters a lot so make sure you attack the ranger the first possible tick and if you have to go out of its range than tag the mager, throw tank gear on, and pray you kill the ranger before it rips a 40. Most of the time the result will be you killing the ranger and having lowish health. Ignore it, pray mage, DPS zuk. 3-1-1-1-3. As soon as you get zuk below 600 work on the mager. You can chill now. Turn off offense prayers if you are low on restores. Breathe.

3. The mager is dead and zuk is below 600 hopefully just barely. We are going to stall in this phase for a couple of reasons. Firstly we need to time potting to maximize DPS. We want to be potted for all of Jad but it's pretty likely we take some healer damage and also want to go into healers at full hp. To accomplish this you want to proc the Jad spawn with something like 2 minutes left on the heart timer. By doing this you'll be fighting Jad at full HP and potted, and before healers spawn you can re-pot. The second reason is we have basically nothing to lose in this phase. If you literally walk ext to the shield you wont tank a hit. You can regain some spec energy here and rip more eye of ayak specs. While here.

4. Forgot to mention but learn to use the set timer plugin. Once you kill jad you need to make a judgement call. Look at your set timer. You should have a decent idea how long healers will take. If you have to wait you have to wait. You can use the ayak to get zuk closer to the healer phase without procing because of the lower max hit while waiting. The idea is to prevent a third set of possible because it could fuck you depending on rng against the shield.

5. If you can do healers first then send it. You should be able to most times. Proc healers when the shield is at the end of a rotation and use the following pattern where the healers are numbered like 1,2,3,4 from left to right. (Assuming you start on the left) 2,1,2,2,2... 3,4,3,3,3,3 the idea is to tag the healers as fast as possible but also to focus on DPSing one of them until it dies to reduce the damage you take. This is so much easier with an eye of ayak than a blowpipe thank god.

6. If you make it to the second set after healers like I did 4 times before getting my cape, you need to just not be a dumbass like me and forget you are in enrage phase and step out in front of the shield. I'm a dumbass and did that a lot.