Detect Crabs

For the duration, you know if there is any Crustacea or Arthropoda within 60 feet of you, as well as where the creature is located.

The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, or a thin sheet of lead. The range of this spell is doubled if you are underwater. 

Unstable Spell. Keep track of the amount of times you cast this spell per day. After casting the spell, roll a d100. If you roll equal to or less than the number of times you have cast this the following effect occurs: You are permanently transformed into a giant crab.