He's big, he's got a crown, and goes great with toast, yes I'm talking about the Royal Jelly, but about 80%+ of the randoms i've grouped with don't understand how to fight him. The last time or two I fought him, I suddenly realized his pattern, and add that to the average healing he does, It's not about a dps race, it's a battle about timing.
1. Preperation - When you fight a royal jelly, the only thing you NEED is a sword, and a few friends with swords. Ideally, I'd reccomend a sword that has a circle slash, such as the calibur series, but that's just me. The calling about needing vials, poison, shock, flame, curse... Those are helpful, but ultimately unnecessary, for if you get the timing right, even 3-4 ticks of healing between party attacks shouldn't cause any issues.
2. Battlefield understanding - The King jelly's room is broken up into areas through respawning breakable blocks, including 2 block clearers, and 4 detonator blocks. In each corner of the room there is a solid block, that gives you a position to fall back to in case the angry king goes after you.
3. The King Jelly's attacks - For being such a problem to most people, he has a minimal amount of actual combat abilities. He can and will heal damage at a regular rate through snarfing up smaller jellies, but that is mostly unimportant, for a party should be able to outdamage the 50so heals that happene every few seconds. Poison can help here, but if you don't have it, don't worry about it. His normal attack is like any normal jelly, charge up, and strike at anything within melee range, where this ability also spawns multiple jellies. This attack also has a fairly long cooldown. Between the cooldowns, you can easily get off a full combo/charged attack of your sword, and get out of range before he attacks again.
At lower health, he sometimes goes pink and is angry, which puts him under invulnerable status and spins all over the room, spawning smaller jellies. The corners as stated having the permenent block, are safe havens from his tirades. One note is while under this effect, he does not heal so you don't have to worry about that.
One important last thing to note, is the Jelly King is completely immune to knockback, and the main reason I reccommend the calibur series and the like. Getting three hits off a single charged attack for me, dealt approximately 450 damage, with a tempered calibur.
4. General tactics - You do have to focus the King foremost, but focus on living over taking him down. His healing, although lots of people panic about it, is inconsequential if the entire party attacks at good opportunities. I could see a blast bomb user being handy if they could keep blast bombs going to keep the swarms away from the party. If a person singular needs to back off to clear out the swarm around him, there shouldn't be an issue, but try to get back in to hit him as soon as possible. As stated his regular attack is on a fairly long delay so you have a good chance to duck in, hit him a few times, then get away long enough for him to attack everything, then repeat as necessary. Between angry spurts, he usually does 2-3 normal attacks, usually giving enough time for one good volley between running from the spinning jelly, but if you can't reach him because his anger took him too far away from you, and the swarms are all around, it's best not to worry about it that time, and get into a better position next time, for if you just try forcing yourself through, most likely you'll get there right when he goes invulnerable, and get plowed to the ground.
That's what I've seen and felt about the Jelly King. It's just a timing battle, and not gear, so with good focus, you should have your gems in no time.
PyreLight
1. If you're spending time to charge instead of wailing on Royal Jelly and not just repelling small ones away from you, it lowers DPS for the group.
2. Solid blocks are bad to go behind, as small jellies will completely surround you and make it impossible to repel them away. And the Royal Jelly himself could just move right up and corner you, too, and then you're pretty shanked.
3. Poison is fairly required, as most people CAN'T outdamage his healing if they're running back to corners or are only using Tier 2 weapons. And if you're not damaging him fast enough, he won't hit his second stage and small jellies will simply pile up on you.
4. Everytime after he berserks, he'll attack exactly once before berserking again. Use stun vials to take advantage of this and get more safety time to just wail on him like an epileptic ragdoll.