Okay, in that case I think it's needs a bit more detail to specification to make enough sense and balance it out. Firstly, I'd suggest a certain range of blocks (maybe 2-3) in which you must left-click THE TARGET for the deflect to take effect, then the time margin would set in and if they use an attack against you it will deflect. To me it seems better to think of it as parrying rather then deflection. Secondly, to trigger the evading effect you'd just have to tap sneak (I say sneak because it seems more realistic. It would equate to the chiblocker's noticable physical movements when directly evading an incoming attack. Plus, it doesn't have to slow down a skilled chiblocker if they jump and sneak on the go), but no short range is required so you can dodge at any distance, but you cannot deflect at any distance, only within the specified range of the aimed target. The same time margin would apply to dodge as it would deflecting.
The reason for this is because realistically chiblockers don't deflect ranged damage (especially not elements), but they do something similar with melee attacks, which is how parrying works. That is how I can see it being worthy of implementing otherwise it would be overpowered and illogical for an chiblocker to just defect the damage of, say, an EarthBlast from about 10 blocks away.
Also, I don't think this ability should be effective by chance; I think it should work 100% of the time otherwise in some situations it'll be a waste of an attempt using it and you'll be stricken with a cooldown for something that didn't work. I think it should be based on timing; judging when the opponent will use an attack to deflect the damage or seeing an attack closing in and timing it right to dodge when it's about to hit you.
Finally, I think that when it comes to deflecting a fire-based ability that it should deflect perhaps only the initial damage which would not include the burning damage because that would not seem feasible within the chiblocker's capabilities. They themselves can only strike physically, so manipulation of physical damage would pertain to that. However, they do not have direct control over fire like a firebender does so they would not be able to actually cast the burning back unto the attackers through any of their physical means.
Other then that I think your idea is pretty good and could work. The dodging makes sense and, of course, configurable activation time is wise to include. I would like to see how this would make attacking chiblockers, so nice suggestion.
