If they manage to make contact with the player, They will jump on the player for a second before stunning them like a monkey would.
After doing this, the player will be stunned for roughly 3 full seconds and will drop several gold chunks, which are taken from the player's inventory. The Leprechaun may collect these chunks of gold while the player is stunned, and if they manage to collect enough gold, they will teleport away to a far away, random section of the level. The player may relocate the Leprechaun and retrieve their money if this happens.
Unusually, Leprechauns are worth 0 favor points when sacrificed at an Altar, meaning they cannot be used to earn a reward from Kali. Despite this, Altars are still a reliable finisher after stunning a Leprechaun, as they will still drop a Four-leaf Clover after being sacrificed.
The gold stealing and teleporting properties of Leprechauns are a reference to Nethack.