This Tiny beastie could be the scariest thing in the whole dungeon.
This little monster was locked away in a stasis chamber by its creator because of the insurmountable damage it could do if released into the surface world. This parasite exists to feed, control, and multiply. It isn’t too picky about its intended prey.
This Tick is about the size of a common frog. The new host must make a DC 14 Fort (Con) Save to resist the beastie’s physical imposition. Once it attaches to the back of a humanoid host, or possibly an animal in a pinch, it begins to burrow inside its host. The tick secrets a special gel substance behind it to seal itself in and prevent further damage to the host. But that’s not the worst of it.
Mind Control: Once attached/embedded within a host, a fierce battle of wills begins between the tick and the host’s mind. The new host must make a Will save DC 12 to resist the initial imposition of the tick’s commands.
The Possessing Tick is a half arcane construct/half living spider inhabited by a minor demon with delusions of world tyranny. Its creator has locked it in a hermetically sealed box and bound the spirit to it. Breaking the ofuda seals and opening the box unleashes the creature. Its first goal is to find a host to inhabit.
Possessing Tick: Init -1; Atk bite +0 melee (0); AC 10; HD 1d6+1; MV 15’; Act 1d20; SP Mind Control; SV Fort +1, Ref -2, Will +10; AL N.
Jeff's Game Box 
Also thinking about a wizard’s lab with various glass specimen jars, all sealed with wax. A couple, including this one, have a holy symbol imprinted in the wax. Unfortunately, since the lab is long abandoned, the dust now obscures most of the imprints.
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