I'm not sure where you got the 80k number from. Dominance reads:

> Killing an enemy grants a shield that absorbs 2477 damage for 3 seconds. This effect can stack up to 10 times.

Each stack will absorb 2477 damage. Since you can have 10 stacks at maximum, your shield will absorb 24,770 damage if you are at maximum stacks. Each time you kill an enemy, it will refresh the full stacked amount of the shield. If you have 6 stacks, for example, and kill an enemy, the stack counter will go to 7, and the shield will refresh to 7 * 2477 or 17339 capacity.

Note that each stack will *also* extend the length of the shield by 0.5 seconds, so at maximum stacks, the shield will last for 8 seconds on top of shielding for 24,770 damage.