Summon Felguard is a Wrist slot Rune added in Phase 3 of WoW Classic: Season of Discovery. This Rune is only available to Warlocks. Here's how to obtain it: ...

6. Head to Demon Fall Canyon in Ashenvale and kill Searing Infernal, Felguard, and Mannaroc Lasher in order to loot 12 Mote of Mannoroth. 7. Head to (89, 77) to locate Mannoroth's weapons.