I've cleared Rafflesia twice on my main and once on my alt. All of them were on tank and all using the Brute Force method to deal with the final phase.
I actually think that the Brute Force method is quite a bit easier provided that your DPS is good enough to do it. The damage coming from the Slimes is actually pretty light until you reach the 10th stack which it will likely kill everyone except your tanks.
Here are some tips. (PS. Maybe I should start a 2.2 Tank-specific Tips Thread, as a follow up to the EX Primals thread from 2.1)
Bonus non-tank advice for this fight:
- Rafflesia should be tanked in the center of the room but it needs to be repositioned and refaced frequently. Your goal as a tank is to position Rafflesia in such a way that the tank's back (Rafflesia's front) is facing an old briar patch. The reason you want to tank her this way is because new bulbs cannot spawn on top of existing briar patches. The new bulbs will now spawn at the sides and back and not the front and the devour target doesn't to have to run in front of the boss to get to a briar patch. By doing this, you're maximizing the usable space for the rest of your party for Thorn Whips and Devours. Very important.
- Tank Swap at two stacks. The obvious benefit is that this is the minimum amount of stacks a tank can take while allowing for the other tank's stacks to expire. You're taking less overall damage. A more subtle but very important benefit is that every cycle of Rafflesia's rotation contains two Bloody Caresses. Between every devour is two stacks. Swapping at two maintains a rhythm where the tank swap occurs at the exact same time of every cycle. We tank swap on the Bloody Caress that happens after Devour/Spit. (Note: Depending on when during the cycle Rafflesia transitions into Phase 2 @ 70%, this might stagger your tank swaps. This is easily fixed by delaying one tank swap.)
- A good time to reposition Rafflesia is during the tank swap. There is no danger of a cleave happening and you have plenty of time to reposition before Blighted Bouquet. As the new tank takes Rafflesia from the old tank, he should reposition and reface Rafflesia (if necessary) so that his back is to an old briar patch. All you really have to do is have your back to wherever you want to face/move Rafflesia as you Provoke and then move backwards into the patch.
- Accuracy cap seems to be 489 or 490. I have parsed a miss at 485 but not never at 490. There are reports of (very infrequent) misses at 488. FYI, Accuracy cap for T7 is 491 or 492. I don't know the Accuracy cap for T8 yet.
- Whichever strategy you're using, it's a good idea to tank Swap once in the final phase. While Rafflesia no longer does Bloody Caress, the benefit is that your first tank can blow all of his defensive cooldowns for ~40% to ~20%, and the second tank can blow all of his defensive cooldowns for ~20% to 0%. Plus, Warriors have Unchained so you're minimizing the amount of time your tanks collectively spend with their tanking stance damage penalty.
If you're going to do the brute force strategy, delay your transition into the final phase so that Rafflesia's HP drops past 40% immediately after the yellow Devour mark appears. Rafflesia will not transition into the final phase until she has completely finished the entire Devour sequence: Thorn Whips -> Mark -> Draw-in -> Devour -> Spit. By doing this, you should be able to cheat out an extra few percent worth of damage before the DPS race begins.I'll post a video of this later, showing all of the above from Tank PoV.
This week, we were able to get her down to about 35% before the final phase actually started and killed with over 10 seconds to spare. If you're not able to beat the enrage timer, (assuming everyone is at least i90) you either just need a cleaner transition into the final phase or your DPS just needs to play better.