Last thing the party can recall is their whole world going black. Now they wake up in a dank, dimly lit cave with no sense of their location or surroundings. They venture for a while, lost, directionless, until coming upon a giant rat. Thugwump the Barbarian is eager to turn it into a delicious rat jelly, but Aidan, the Fallen Aasimar Eldritch Knight intervenes. For years, Aidan has felt an otherworldly pull on his soul: East. He knows not what lies to the East, only that it is where he must go, East.
“I cast Infestation,” Aidan’s player says. The rat fails its saving throw and is swarmed with gnats and fleas biting at its skin, dealing 3 poison damage. Then the player rolls a d4, the rat moves a space away, and Aidan exclaims “Aha! I know which way to go now! East, my companions. Always to the East.”
“What the hell?” the DM asks.
The Conjuration cantrip Infestation reads:
You cause a cloud of mites, fleas, and other parasites to appear momentarily on one creature you can see within range. The target must succeed on a Constitution saving throw, or it takes 1d6 poison damage and moves 5 feet in a random direction if it can move and its speed is at least 5 feet. Roll a d4 for the direction: 1, north; 2, south; 3, east; or 4, west. This movement doesn’t provoke opportunity attacks, and if the direction rolled is blocked, the target doesn’t move.
May this spell be used to create a makeshift compass?
Whatever Aidan’s player rolls, based on the response of the rat, the player will be able to discern which direction is East. Of course the player needs his Aasimar spiritual guide to be right about East being the correct way to go, but assuming he’s getting good direction (sorry about the pun), does this work?
No. No it does not.
While Aidan’s player knows what was rolled on the d4 to determine the giant rat’s random direction, Aidan (the character) does not know the die result. To him, the rat moved in a random direction. All he’s done is piss off the rat and ruin Thugwump’s breakfast.
But could it work? Maybe, and in exactly one scenario, and this happens to be it.
Fans of the Diablo franchise may recognize Aidan as the Dark Wanderer, the fighter –struggling to contain the soul of Diablo– driven ever towards the East. Could a DM allow this Diablo-inspired Fallen Aasimar Aidan to use Infestation to enact some sort of divination blood ritual on the rat to learn what direction to travel in?
I’d allow it.