Shapeless Pulp has 150 health and spawns in the Deep North.
It takes extra damage from blunt, frost and lightning; it resists slash, pierce and fire; poison does nothing to it at all.
Its only attack is aoe, 110 poison and 20 blunt.
Some of what it throws is elemental, so poison resistance is worth having.
You cannot block aoe, so give yourself room to dodge instead.
Of everything craftable, 
Lightning Strike, 
Frostfire Sledge and 
Thunderblood Sledge put the most damage through what it resists.
It always drops BlobMorkMini.
Shapeless Pulp is a hostile blob found in Mörkhalla in the Deep North. It has 150 health, is weak to blunt, frost and lightning, resists slash, pierce and fire, and is immune to poison. Killing one leaves 1 to 2 
Tiny Pulp behind, along with a 50% chance of 
Dead Pulp and a 10% chance of a 
Pulp Trophy. A Hexahedric Pulp produces a fresh one every 5 seconds, so a room only clears once the source is dealt with.
Weak to blunt, frost and lightning; resistant to slash, pierce and fire; immune to poison. A sledge handles both the parent and the pieces. Its only attack is an unblockable burst for 110 poison and 20 blunt, so a shield does nothing and poison resistance does everything. It drops Dead Pulp half the time, the material for the 
Blob Bomb: Pulp, and a 10 percent Pulp Trophy.
With devcommands enabled, this spawns Shapeless Pulp in front of you. The third number is the level: 3 spawns a 2-star.
Creature ID: BlobMork · all console commands and IDs