You get ressource on heavy attack when the attack is fully charged and successfully hit.
Heavy attack ressource gain is based on the lengh of the attack, the more slow the attack is, the more ressource the attack give.
Here is the base value of heavy attacks with no passive modifier :
- Bow HA: 2724 Stamina
- Dual Wield HA : 1667 Stamina
- 2H HA :2426 Stamina
- 1H&S HA : 2014 Stamina
- Fire/Frost staff HA : 2823 Magicka
- Shock staff HA: 3633 Magicka
- Restoration staff HA : 3219 Magicka (note there is a 30% more ressource passive that can be added with Cycle of life) : 4184 magicka
- Werewolf HA : 1617 Stamina (note there is a 100% more ressource passive that can be added with Pursuit) : 3234 stamina