"This massive gelatinous cube has a short fuse and loves to throw his weight around. When his royal tasters are absent a poisoned parfait would be a royal pain." — Monstrous Codex: Royal Jelly
The Royal Jelly (also unofficially known as the Jelly King) is a gelatinous cube about 5 times the dimensions of the basic pink cube, adorned with a white and purple crown on its top.
The Royal Jelly is weak to shadow attacks, and has resistance to piercing.
Tread with caution when you enter the slime-covered halls of the Royal Jelly Palace (see also: Mission 5-2 The Sovereign Slime). Recon Knights have gathered that this ancient, open-air castle has been overtaken by a legion of slimes, the most fearsome of which is a 'Royal Jelly.'
Like any unruly king, it has a short fuse and loves to throw its weight around. We cannot be certain under what lineage or authority this oozing aristocrat claims noble descent, but we would still caution those traveling in its palace to stay vigilant and come prepared with Poison vials and weapons, in addition to a full complement of knights!
The Royal Jelly is capable of automatically destroying breakable blocks that he comes into contact with. His walking speed is incredibly slow, but like his lesser brethren is capable of using a full-bodied tackle for an instant burst of speed. He uses a 360 degree spin attack with substantial knockback, and occasionally summons four Jelly Cubes to assist him. Coming into direct contact with him will repel you backwards, dealing moderate damage and knockback regardless of whether he was attacking at that given moment. The Royal Jelly is also assisted by Royal Polyps which are stationed around the perimeter of his chambers - they can create numerous Royal Minis as well as shooting piercing barbs, both of which are capable of healing the Royal Jelly. New ones appear at the beginning of each phase.
When he loses his crown on the final phase, the Royal Jelly will begin to periodically go into a rage. He will turn pink and start to spin in a counterclockwise fashion. In this state he's impervious to damage and can deal a large amount of damage with a fair amount of knockback, but because of the attack's indiscriminate nature it's easy enough to avoid.
There are two main approaches to killing the Royal Jelly: blitz or starve.
Knights can overcome the Royal Jelly's healing capabilities by simply overwhelming his healing with a huge damage output; no matter how many royal minis surround him, he can only absorb them so fast. If they keep the pressure up, the king will fall.
If knights kill the Royal Polyps (and any lingering Royal Minis), then the Royal Jelly loses his ability to heal, and the knights can wear him down at their leisure. This also greatly reduces the number of enemies in the room, making it much easier to maneuver and avoid damage. More Royal Polyps will appear at the beginning of new phases of the fight, but do not seem to respawn on a timer until the final phase when the Royal Jelly begins his rage spins. Note that the Royal Polyps have considerably more health than regular Polyps.
Starvation will never kill the king as fast as a well-executed blitz, but it is more forgiving of mistakes and opens up a number of tactical possibilities that simply aren't viable when using the blitz.
Note: this technique is disputed, see the discussion page.
The Royal Jelly and Jelly Minis do normal damage, but Jelly Cubes and Royal Polyps deal piercing; none of which inflict status effects. The Wolver line and Bristling Buckler are popular choices for protection, but one may employ a Swiftstrike Buckler for added weaponspeed. Because no enemy in the Palace inflicts any statuses (Besides Lumbers), a Chaos set is also a viable option. The Chroma line is also clearly fitting with its Damage Bonus vs. Slimes perk, but has more limited utility outside the Jelly Palace.
When blitzing the Royal Jelly, it's important to have high damage output to limit his window for healing. Swords are generally favored, both because of their higher damage and because the swarm of jellies that surrounds the king under this strategy makes it difficult to hit him with gunfire. The Nightblade line or Dark Retribution are popular choices for the fight due to their shadow damage. The Vile Striker is also a good option due to the chance of inflicting poison.
When using a starvation strategy, weapon choice becomes less important but Shadow damage will still come in handy. Knights may also wish to employ some form of crowd control, such as a Freezing Vaporizer or Graviton Vortex.
Status vials - particuarly Poison - are very helpful in any strategy. However, a Maskeraith is a viable replacement for Poison Vials, as its Quill attack can both Poison and deal additional damage for every Quill attached to the King.
Unbreakable blocks near the corners of the room block the humongous Royal Jelly, and can be used for shelter from its attacks (but beware being trapped by his smaller brethren).
Standing on top of a regenerating block pad will prevent the block from reappearing; this can be used to keep an avenue of escape open. You will receive a small amount of damage each time your body blocks a block from spawning, though this block-blocking damage can itself be blocked with a shield.
Video Walkthrough: Royal Jelly Battle Guide, Strategy and Walk-through Guns Only Chanlange:https://www.youtube.com/watch?v=QrBgVpVdeCU&t=186s
- The Recon Module: Royal Jelly Palace can be obtained in front of the lift right after killing the Royal Jelly.
- The Royal Jelly's health varies by the number of players in the party. Under some circumstances, he can be easier solo than in a group.
- The first three Jelly Cubes that spawn at the beginning of the battle along with the Royal Jelly himself are the only monsters in a boss battle that have Crown, Heat, and Material drops (Excluding the Heart and Vitapod Drops from Surgebots in the ICMF, and Slag Walkers and Guards in the FSC). Any other Jelly Cubes spawned by the Royal Jelly besides the first three will not drop Crowns, Heat, or Materials.