So What Else Happens If I Roll a 27 To Hit?

As a card-carrying member of The Order of the D30, I bring out my golden lump of randomness at each game. The houserule for d30 use as recognized by The Order is as follows:

Once per session, a player may opt to roll the d30 in lieu of whatever die or dice the situation normally calls for. The choice to roll the d30 must be made before the roll, and the d30 cannot be used for generating character statistics or hit points.

So if your character is swinging a dagger for a paltry 1d4 damage, you can instead use the d30 to roll damage upon a successful hit. A dagger stab for 27 hit points of damage? Nice. My players often use the d30 for damage rolls as a potential hit for 30 points of damage to a major villain can be a real game changer. (Allows for those "epic moments" too.)

However, the d30 has been used for those To Hit rolls where the odds are stacked against you. The party is moments away from a TPK, and you need to roll 18 or more to hit the mutant pounding you? Whip out the d30 to increase your odds. However, one player pointed out that I'm usually pretty generous with damage bonuses when a natural 20 is rolled in combat. "But there's never a damage bonus when we roll more than a 20 on the d30," he said. "Shouldn't we get something extra?"

At first I thought it was a bit cheeky to ask as the d30 already increases your odds for a successful combat hit. What more do you want? But then I remembered that those epic moments is precisely why I use the d30 in my games. So here is a new "d30 combat roll" rule I'm mulling over:

If the d30 is used in a To Hit roll, any rolls from 21 through 30 will be considered a critical hit. The amount rolled over 20 (X) will be given as an Xd4 damage bonus, ie, a 21 will grant a +1d4 damage bonus; 22 will grant a +2d4 damage bonus; up to 30 which will grant a +10d4 damage bonus.

Whadya think, sirs?