Tuesday Quest: Ragnarok (for those bollas)

30 energy / 5 rounds.  So-so drop rate, though which bollas you encounter are random.

My team (for those that do not have super-amazing cards):
Leader: Askafure+ (I actually got a Yasha from the Sleeping Oglier quest, but was not leveled, though it may have been good for this particular quest.  If you wanna be ballsy you can put a shadow damage enhancer card here - it may speed up stage 4 and 5 a little.)
Erinyes+ (safety precautions for stage 4)
Jotunn+ (another safety precaution for stage 4 and 5)
Banshee+ (required for stage 5, makes stage 4 much less painful)
Dark Witch+++ (or any high DPS card to get you through stages 1-3; since I already had 2 dark cards I figured why not 3.  If you are fortunate to have golem/lenanshe/some card that does a percentage of the target's HP as damage, that'd be ideal)
Follower: Encantado+ (Yasha would be ok if you are good with heart management).

Stages 1-3: I dunno if the enemies are random, but there are 2 enemies per round hitting for around 2000+ each.  I'd prefer to knock them out one at a time.  Don't have to be really slow about killing the second one on each round, but enough time to get Jotunn and Erinyes' skills ready for stage 4.  Having good DPS will soften how many hearts you need on the board initially.

Stage 4: The holy/dark bolla hits 12764 damage every 3 rounds.  It's much less nerve-racking if you have Encantado than Yasha.  Having really high HP may also be a hindrance since you are trying to maintain a certain HP threshold for those skills to activate.  This is actually the hardest round with this strategy.  Use Pestilence, get to 40/70% HP, and then make  combos each turn to get enough hearts on the board to recover after getting hit. While the bolla doesn't have much armor, it has a lot of HP (each Pestilence tick did around 11000 damage).  Just get to your needed HP and win the war of attrition with Banshee, Jotunn, and Erinyes' skills.

Stage 5: The same deal, just easier.  Also more annoying since this bolla has 1800 defense and even more HP, forcing you to rely solely on skills for damage (poison ticks for 20000+).  It does 22200 damage every 5 turns.  But with this strategy it just means 2 more turns to get to the HP you need to survive.  Note that this is currently the only time a fire bolla can appear, and I'm assuming it only has a 33% to show up.