Paladin Prot Talent: Reckoning
On all vanilla private servers I have played on reckoning either only stacks with yellow spell critical (not white damage critical) or it stacks with both but never drops until it is dropped.
Proper Reckoning Behavior:
1. If autoattack is on and you are targeting a player any crits you absorb BETWEEN AUTOATTACK TICKS result in an extra hit the next swing. IE: You are face to face with a rogue. He crits you 2 times between swings of your slow 2h. Your next swing = 3 hits.
2. If autoattack is off, any crits you take add extra attacks on the next swing up to 4 extra hits, or 5 total hits on the next swing.
EXCEPTIONS: If your autoattack is ON and the next tick of your autoattack tick doesn't result in a swing for ANY reason (ie: because you are: stunned, out of melee range, gouged, blinded, scatter shotted, sheeped, feared, or facing the wrong direction) then the additional attacks (reckoning charges) are dropped. Your next swing will not result in extra hits unless you properly stack more extra hits in the intermediary.
DROPPED CHARGES:
If autoattack is not on and you are building "reckoning charges" (extra hits) by taking crits, you can save these extra hits until you turn autoattack on UNLESS YOU: mount up, get feared, get sheeped, blinded, scatter shotted, zone into a new instance, use a flight path, end a duel, use an invisibility potion, or die. [[NOTE: Anyone linking to Zalgradis 3 PvP video to argue you can mount/use invis and STILL retain charges-- that was PRE PATCH 1.9]]
Evidence:
In this Live Vanilla video you can see the behavior of the reckoning talent and the author periodically shows "tips" that talk about when charges are dropped.
[video=youtube;lQzxgkXRA1Y]https://www.youtube.com/watch?v=lQzxgkXRA1Y[/video]
How Reckoning Behaves with Seals:
Most seals can proc multiple times when a reckoning "bomb" of more than 1 hit per swing is dropped.
EXCEPTIONS: The two added damage seals, Seal of Command and Seal of Righteousness. SoR only adds extra damage to ONE hit per swing no matter how many reckoning charges are dropped on an enemy. Seal of Command can only proc ONCE per swing no matter how many reckoning charge hits are dropped on an enemy.
Misc: On many private servers, ultra low level mobs critting you doesn't add a reckoning charge. It should. On live however you couldn't just "sit" against mobs and get charges. For some reason you had to spam your sit key and wait for your reckoning counter addon to tell you when a charge was added. I believe this was an exploit of Blizzard's attempt to stop people from gaining charges by sitting in front of mobs, but it was still doable with the "spam x" method. I have NO IDEA how the actual mechanics of this worked.
In short this exact mechanic or bug, whichever it was, will be difficult of not impossible to replicate-- but it was possible to stack reckoning charges off of mobs of any level. I used to troll people in duels all the time by stacking charges from Dun Morogh mobs. [[Update]] After some reading some stuff that jogged my memory, I believe in 1.12.1 it worked so you wouldn't stack charges while sitting for WHITE ATTACKS unless you did the sit key spam trick but sitting to get charges from YELLOW ATTACKS did work without the spam sit trick.
Further reading:
http://blue.cardplace.com/cache/wow-paladin/1069149.htm