Lester

Bio
Lester is a farmer who is at the edge of town. He stands by cows and says that you must blow up the Abyss entrance with a Rune bomb

Diablo Hellfire
In Diablo Hellfire, Lester would do the same thing except he gives you the Auric Amulet instead of Amber.

Rune Bomb
You also recieve the Rune Bomb for killing Diablo on level 16.