Unlock the Necromancer Golem by completing the class quest at level 25
Travel to the quest location in Kehjistan
Complete the quest to gain the ability to summon a Golem
Open the Skills menu
Assign the Golem skill to your skill bar
Use the assigned skill to summon the Golem
If the Golem disappears, resummon it with the same skill
If you are not a Necromancer, you cannot summon a Golem