Active Defense!

I was reading through the Dungeons and Dragons 3.5 PHB the other day, and I noticed something that is oddly missing from 4th edition: active defenses.

So I decided to make some up. I decided that there should be a dodge for rogue-ish sort of characters, and block for fighter types.

Dodge is based on Acrobatics, and is more or less just a straight check with that skill with a DC based on the roll result that caused the hit. For instance, a character gets hit by a monster who rolled an 18 on the d20 and had a +6 bonus. His dodge check has to pass a DC of 24. If he succeeds, he shifts one space (getting out of the way) and avoids all effects of the attack. If he fails, he may still shift one space, but he still takes the damage and effects, in addition to being knocked prone.

Block is similar. It requires a shield, but the DC is figured the same way. On a success, the character is unaffected by the attack. On a failure, he is pushed back one space (this is forced movement) and still takes all the effects.

I've been trying to think up a way to do parrying, but my ideas are all mechanically similar to either dodge or block. Any ideas? (I'm pretending here that anyone actually reads this blog. Heh.)