Abin Sur's Lantern and Eye of Ekron give Krypto a decent boost to Will and power damage, along with the scaling from Ekron's mod but because Krypto has less Will scaling in his kit in comparison to other Controllers, these two items should provide all he needs.
Atlantean Royal Seal provides additional damage and HP to survive engaging targets in melee, as well as adding more crowd-control to Fetch, Vigilance boosted On The Hunt and his ultimate.
Metallo's Heart further boosts Krypto's ability to survive being the only melee Controller while also working with the effect of On The Hunt to reduce enemy attack speeds. These two in combination with one another can outright prevent a large amount of basic attack damage being dealt by the enemy team, making up for Krypto's positional shielding ability and lack of a heal. The additional cooldown reduction is also very helpful.
Kryptonian War Armor provides the power armor needed to survive the inevitable power damage the enemy will throw at you in order to remove Met's Heart's aura from play, while the extra HP capitalizes on his higher armor, the move speed allows easier dodging of skill-shots and the increased HP-regen and healing help counter Krypto's lack of a healing skill.
Psi-Scimitar provides a large boost to power damage while also granting some much needed Will regen to make up for the lower maximum Will Krypto ends up with, allowing him to reliably combo his skills for the Scimitar's skill effect, keeping him in combat and dealing damage.