The spells are given at levels 30, 58, and 63 I believe. You cast on a mob, and whenever it hits anything in melee combat, it takes damage (Reverse damage-shield). The level 58 one is 10 damage and I believe the level 63 spell is 14 damage.
It's not that significant but it does add up, in some cases more than others. Casting it on a phantom-striking mob in a level 65 raid will mean it takes around 600 damage every time it phantom strikes.
Which jolt spell is unresistable? Even Wizard relic one is magic check.