b) If you want to summon you use his npc_pch_id not npc_id,
//summon [10+npc_ID] [amount]
example: NPC ID is 26186, so you use this command:
//summon 1026186 1
Also npc_name its not his client side name like "Antharas", you use his server name antaras_min / antaras_normal / antaras_max.
//summon antaras_normal 1