Sense invisible

Monsters which "sense invisible" can tell where invisible opponents are, and have bonuses to perception in other cases.

Effects of monster sense_invisible:

• For anything that just checks you.visible_to(monster), it's as strong as see invisible.
• Monsters with “sense invisible” have a better chance of noticing stealthy players than those with “see invisible”.
• “sense invisible” has some effect on a monster guessing an invisible foe's position: Without, it guesses within radius 2 around itself, with within radius 3. This makes it easier to escape from non-sensing monsters, but apparently makes sensing monsters less likely to guess your position when you're close (within radius 2) of them.
• Slightly decreased stabbing chance.
• An effect on beam targeting fuzz
• Friendly summons with Sense Invisible are helpless against Unseen horror.

Current player "sense invisible":

Player can tell the locations of revealed invisible monsters that stand in water or that are in certain clouds.