Dragonlance Guidance

You touch one willing creature. Once before the spell ends, the target can roll a d4 and add the number rolled to one ability check of its choice. It can roll the die before or after making the ability check. The spell then ends.

Alternatively you may cast this spell to commune with a deity. To do so follow the skill challenge your DM instructs you to complete. You may add 1d4 to one of those skill challenge rolls