To spawn the Elder at the Shaper's Realm, have the Elder influence spread next to a Tier 16 map and defeat the Guardian to turn it into an Elder-influenced area. Once that's done, defeat the other Guardians to spread Elder influence to those maps. Once all four Tier 16 maps are Elder-influenced, the Elder will spawn in the Shaper's Realm. Then, defeat the Elder Guardians and finally the Elder.