The -3 mana cost on wands no longer applies to Tempest Strike, whereas it has the “spell” tag.
Tempest Strike’s mana cost is rightly reduced in the skill’s talent tree. But not when the skill is used.
For example: with 4 points in Ancestral Swiftness the cost is reduced to 8 mana. With a wand, it is reduced to 5 mana. Which is clearly displayed on the skill in the talent tree.
But when used, Tempest Strike actually costs 8 mana.
It was working perfectly before yesterday’s patch.