Festersand Serpent

The Festersand Serpent is a Hardmode desert boss. Boss Checklist says: Use a Festered Bloombud in the surface desert. Using the bud has no extra progression gate. The recipe needs Souls of Night, so you have to be in Hardmode to craft it.

The body is longer than the Bloomsand Serpent. On all four legendary lines, the old Aquatic Scourge trial seat now binds this fight.

Summon

At an Iron Anvil, craft a Festered Bloombud from a Thorned Bloombud and Souls of Night. Use it on the desert surface. You cannot use another while a Festersand Serpent is already up.

A Thorned Bloombud still needs the Eye of Cthulhu flag to be used. The Festered Bloombud itself does not check that flag.

The entrance has two beats and does no damage. Corrupt stain first spreads along the sand from the breach, and ichor bubbles burst out of the ground. Then it leaps over your head, sheds a harmless ichor rain, slams down, rears, and roars.

Phases and pools

The body crawls on the sand. Cysts light first, then drip slow ichor globules. That is a regular attack during the crawl. Those drips do not leave pools.

Spit shots leave gilded ichor pools. About 22 pools can sit on the field at once. They last about 20 seconds, then dry. Pools burn, and a later breach can ignite nearby ones.

Around 62% life it clears shots, coils, burrows, and bursts skyward. In the air it convulses. Old husk tears from head to tail, and seven new segments grow from the split. That scene does no damage. The body is longer. Turns are slower. The fester-storm opens fully when it slams back down.

Around 28% life every cyst flashes and it roars into the end. That roar does no damage. The first attack after it is the field detonation.

If the player moves far, phase one inserts a breach fount to close the distance. After the molt that chase becomes an ichor-gate rush instead. After either chase, it must complete a cycle of other attacks before using that chase again. If you leave the fight it tucks its legs and burrows out. The death scene lasts about 6 seconds. Life is locked and it does no damage.

If you stay in the air or on platforms, several ground attacks become coil, a gate rush, or the body split instead.

Moves

Throughout the fight

Sweep spray. It tracks while crawling, inhales with a slight lean back, then fires ichor globs down a pair of symmetric lanes. Landings sow pools. The lanes open from the inside out, then reverse and close. Before the reverse you hear a rising cue and the head flashes. When the head flashes, the opposite gap is the safe lane. The seam between the two lanes never fires. At very close range the volley does not fire.

Dust-lane dash. Same tell as Bloomsand: it opens a runway, drops low, pulls back, and a dust line draws on the ground. When the line stops, the heading is locked. It burst-dashes, hard-brakes, then repeats. Phase one does three dashes. After the molt it does four. The wake throws ichor: rain drips and pool drips alternate. After the body dash, ichor drips on the ground still deal damage. If the player is too close, it backs away first.

Sticky sores. It rears back and slings sticky fester cysts that bracket where you were. Each cyst sticks to a brick face, swells on a rising cue, then fires a vertical ichor geyser on a stagger. Small pools stay near the ground. The spacing between landings is the standable gap. Remaining on that brick column while a cyst swells takes geyser damage.

Breach fount. It burrows and closes from underground. A fester breach mound rises first. That mound is the rupture. It will not move. Then it bursts out in a straight line, sprays about a half-circle of ichor, leaves escape lanes on both sides, and ignites pools next to the rupture. Contact damage only runs while the lunge is visible. After the molt it does three cycles. Before that it does two.

Claw slam. It closes in, lifts both pestles overhead, and slams them together. The impact shakes the screen. High ichor globs burst from the slam and fan to both flanks, sowing pools. It slams twice in phase one, three times after the molt. The lift facing is the slam facing. While it slams it stands still.

Coil cascade. It climbs and draws a wide circle around you. The head vomits ichor toward the center. Spokes of rain turn with the body. Spray and rest alternate. During a rest, moving along a tangent or leaving the circle is safe. The center only follows slowly. It does not lock onto you. After the molt the closeout adds a short tangent dash, then a dive back to the sand.

After the molt (about 62% life)

Swallow mortar. The head ducks into the sand and inhales. Dust pulls toward the mouth. A bulge crawls from tail to head for a little over a second. When the wave reaches the head it rears and fires a fester mortar shell that bursts above you into a downward cone of shards. There is a gap directly below. The heading locks before the shot. After about 28% life it fires two shells on a stagger.

Ichor-gate rush. It opens an ichor gate in front of itself and another beside you. Once the exit gate appears it holds that facing for at least about 0.7 seconds. The whole body threads the entrance, pauses, then burst-dashes out of the exit. The exit then walks about a third of a circle around you before the next loop. While it is hidden inside, neither side can land hits. On platforms or a dug-out yard this attack replaces the breach.

Scythe reap. It half-rears. A long scythe cuts its own cysts along one flank, one at a time. Each cut has an arc and a glow first. The burst sprays a directed ichor fan and leaves pools. After the tip clears overhead it also slings a comb of heavy globs. If the cysts are not charged it skips the cuts and only does the short glob toss. While it stands and cuts, the player can damage the body.

Quake pillars. It closes in and lifts both pestles higher than a normal slam. After the clap, ichor geyser columns march out from the impact to both sides. Each column has its own omen disk. Columns sit about 9 tiles apart. The cores are narrow, so the gaps are the hall. While it slams it stands still. After about 28% life the ordinary slam appears less often, and this march becomes the main pestle attack.

Cyst skim. It opens a runway, short-charges, locks heading, and skims past you at speed. Cysts chain-burst from head to tail and throw short-arc ichor off both flanks. A burst cyst stays flat for about 8 seconds. Flat cysts do not light, do not burst, and the crawl drip from those nodes also goes quiet. After the lock it does not turn.

After the overflow (about 28% life)

Field detonation. It plants all eight legs and rears to full height, then roars on a charge. Every pool on the field takes a fuse. When the charge ends, geyser columns roll from its body outward, nearest first. The safe positions are the gaps between pools, not an attempt to outrun the wavefront. The nearest pools still bubble for about 0.7 seconds after their fuse starts. If fewer than four pools are down, it ring-sows extras first. After the attack it pauses before the next move.

Body split. It rears and roars, then tears at a mid-chain cyst seam. The rear half becomes a second serpent. Both halves take opposite corners, then dash at the same time. Their paths cross at you and draw an X. They swap sides and dash again, then weld back together. The four corners off the X are walkable. When it splits, moving to either side avoids the crossing. Standing on the crossing takes both dashes. Both halves light their tells together. After each heading locks, that half does not turn.

Drops

• Cursedflame Bloodfist always
• Souls of Night, Ichor, Cursed Flames, Dark Shards, Ebonsand