Don Colton's Risk Dice Roller

(Risk is a trademark of Parker Bros / Hasbro for their board game.)
Wikipedia Article, Attacking

How many attacking armies
How many defending armies
How many skirmishes (max)

Skirmish 1   1 3 4   3 2 attacker loses X, defender loses X
Skirmish 2   2 2 2   2 1 attacker loses X, defender loses X
Skirmish 3   1 6 6   6 3 attacker loses X, defender loses X
Skirmish 4   4 3 2   1 5 attacker loses X, defender loses X