3 items: Gain Minor Aegis at all times, reducing your damage taken from Dungeon, Trial, and Arena Monsters by 5%.
4 items: Adds 129 Magicka Recovery.
5 items: Your fully-charged Heavy Attacks place a soul bomb on your target that charges as the target takes damage. After 10 seconds, the bomb explodes, restoring 5% of the damage received as Stamina and Magicka, up to 2240 Stamina and Magicka, to 12 group members within 16 meters of the explosion. This effect can occur every 10 seconds.
5 items (Perfected): Adds 1096 Maximum Magicka.
Set Rating: 4 out of 5.
When to use: In groups that need a sustain set.
Where to obtain: Rockgrove Trial.
Set Weight: Light Armor.
Which pieces to obtain: Weapons and Jewellery.
Comments: This is a really good sustain set and easy to utilise as a Tank, doing something you should be doing as a Tank already.
Stone-Talker's Oath - Gear Set Review | Elder Scrolls Online