Most of this game was pretty tame, all things considered, but this boss can die in a fire. Can't say I expected it to be easy, but good lord what a difficulty spike.

My current stats at Team Tank 21 are as follows: Vi HP: 22 Kabbu HP: 24 Lief HP: 22 31 TP 11 Medal Points I stocked up on a bunch of glazed honey and fried eggs. Got one magic seed in there somewhere.

As you can see I didn't prioritize my medal points much, and I think that's my problem here. I didn't find many medals throughout my playthrough and I didn't have much reason to change them around until the very end it seems. Currently I have an HP Plus medal on everyone, a TP Plus equipped and... nothing else that would be even remotely helpful for The Everlasting King. Some poison-resistant stuff and that's it. What medals should I look for?

After many attempts I've picked up that he can only do his restorative attacks while grounded. By attacking in the order of Vi>Lief>Kabbu I can get the max basic damage out while keeping him in the air so he can't heal himself. That works long enough to get him to round 3, but as soon as he brings out the two artifacts that combine everyone's at low enough HP for the artifacts to kill everyone.

For a casual run, you are somewhat under-leveled. Most players will be max rank by the time ELK is fought, or at least very close. If you didn't know, max rank is 27.

How much side-quest stuff did you do? Most medals are acquired through doing quests, or through exploration in general. Your MP is definitely lower than most would do, but you should be able to succeed with enough usage of items and TP.

Also, this isn't exactly the best place to ask for help on a first run of the game. You'd be better off asking about it on the official discord instead.