Player Rolled Defenses (4e Variant Rule)

Player Rolled Defenses
The Player Rolled Defenses variant requires the following:
 * 1) The "10+" for AC, Fortitude, Reflex, and Will defenses for player characters is now a d20 roll ( i.e.  subtract 10 from all the PC's defenses and add a d20 roll )
 * 2) The DM will add the "10+" to the attack bonus of monsters to set a "target number" for the Player Rolled Defense ... this means the DM will not make an attack roll.
 * 3) A roll of a "natural 20" is a "Perfect Defense" and allows the defender to make a basic attack ( ranged or melee ) as an immediate reaction.
 * 4) A roll of a "natural 1" is a "Fumbled Defense" and the attacker scores a critical hit.

When we were working on this variant, we realized the DM's baddies should be able to perfectly defend a PC attack. So, we added a couple more requirements for this variant:
 * 1) A PC attack roll of a "natural 20" is a "Critical Hit", whether it beats the defense of the monster or not.
 * 2) A PC attack roll of a "natural 1" is a "Fumbled Attack" and the target will get a free basic attack on the PC as an immediate reaction.

Keep in mind that only one immediate action is allowed per combat round, if you decide to implement this variant combat rule.

I'm currently using this variant in two 4th edition gaming groups and we're loving it. Both as a DM and a Player, this variant helps our game. As a DM, it seems like it engages the players more and only have to worry about rolling damage is nice ... especially when I've got player's interrupting my actions with immediate reaction/interrupt powers and such. As a player, it seems like my character's fate is more in my hand by making the defense roll ... or not.

I know we added a little more than just "Player Rolled Defenses" by tweeking the "Critical Hit" rules to streamline this variant.