Tenacious Stone Shaper ability 'Powers of the Arcane' tooltip:
"Grants target additional resist pierce
Value:10
Target: Self
Duration: 30 sec"
In duel testing, this does not increase spell pierce beyond the passive 10% acquired in templates. If this is WAI, please remove the word 'additional' from the tooltip.
Slayer Staff /use2 providing no benefit
Re: Slayer Staff /use2 providing no benefit
Seems like you figured it out yourself.