Mustard jelly

A mustard jelly was an intelligent and dangerous ooze, which utilised toxic vapors in combat.

Description
Mustard jellies were large and translucent, making them very hard to see until they attacked. It only gave off a faint odor, which was similar to that of mustard plants. As well as a similar odor, they also shared the color of such blooming plants, being shades of yellow to light brown.

Behavior
Unlike almost all oozes, mustard jellies possessed intelligence. As well as this, many other factors made it a very dangerous species, and was known to be far more of a threat than ochre jellies.

Although they couldn't flow directly through small gaps, like ochre jellies, they could quickly split into smaller halves and make the transition. Once on the other side, the halves could rejoin into the larger forms. Alternatively, the jellies could just eat their way through obstacles, such as wooden doors. It could not climb walls or move along ceilings, preferring to keep most of its bulk on the floor, and stretching upwards instead.

Mustard jellies didn't seem to value treasure, like other intelligent creatures, except for that they could use to lure prey.

Combat
When initiating attacks, the jellies appear in their mustard-colored forms, and formed acidic pseudopods of their own substance. Here, they would thrust towards their opponents, making their victims lethargic and moving at slow speeds. Their toxic vapor could be spread over a 10' radius.

The large jellies could split themselves into two smaller jellies, each having half the health of the previous form. Thus, they could flank an opponent from both the front and the back. The smaller halves could move up to twice as quick.

They were not able to be harmed by standard weapons and would devour any wooden items in their path. They were immune to all electrical attacks, and spells such as magic missile would only cause it to grow larger and heal. Cold damage only hit mustard jellies for half the standard damage. In addition to such defences, they were also resistant to magic.

Society
Mustard jellies were generally rarely found, and if so, were solitary. They scavenged, or set traps, for food.

History
These intelligent oozes originated when a young wizard attempted to polymorph into a ochre jelly. The wizard failed and she was transformed into a mustard jelly. Since the accident, these jellies multiplied rapidly and spread to many areas.