Nexus-Princess Ky’veza is the delve pinnacle boss in War Within Season 3 and this article covers the rewards you can unlock until Midnight hits!
Mount Skin
When you earn the 
Let Me Solo Her: Nexus-Princess Ky’veza achievement by defeating Nexus-Princess Ky’veza in her lair on Tier ?? difficulty alone before the release of the next season of delves, you will receive 
Delver’s Mana-Skimmer Schematic: Hyperdrive.
Helm Transmog
You will receive 
Hal’hadar’s Phasebound Visor when you kill Ky’veza before the release of the next season of delves via My Stab-Happy Nemesis.
Etheric Victory Toy
Completing the Defeating Ky’veza seasonal quest by slaying Ky’veza grants the 
Etheric Victory toy that makes you emanate a void aura for 30 minutes.
Contract Killer Title
Pruning the Princess grants you the Contract Killer title when you defeat Ky’veza in her lair on Tier ?? difficulty before the release of the next season of delves.
Something for Everyone
When Nexus-Princess Ky’veza kills you in a delve, you will receive Let Her Solo Me achievement.
