Ranged matchups: Lane sustain and diving tankiness.
Durability and crowd control
Every 4s your next attack on a champion deals bonus damage, heals you, and permanently increases your health.
Whenever you gain a shield, your next basic attack against a champion deals bonus adaptive damage.
After 10 minutes gain 8 Armor and 8 Magic Resist and increase your total Armor and Magic Resist by 5%.
Heals and shields are 5% stronger and increased by an additional 10% on targets below 40% health.
Empowered abilities and resource manipulation
Hitting enemy champions with a spell grants maximum mana.
After reaching 250 mana, Manaflow Band restores 1% of your missing mana every 5 seconds.
Gain 10% CDR when you reach level 10. Excess CDR becomes AP or AD, Adaptive.
+5 Armor or 6 MR (match-up)
Ornn is often trading in lane with Brittle empowered auto-attacks, making Grasp a great choice for additional damage and sustain.
Shield Bash synergizes perfectly with Ornn's [W] granting you even more offensive trading power in lane.
Conditioning's double bonus resists synergizes well with Orn''s [E] damage as well as role as a front-line tank.
Oppressive lanes: If you're playing into an incredibly oppressive lane (Teemo) Second Wind here will help you survive lane a lot more safely.
Revitalize empowers your ability to take aggressive trades often by buffing the self-shield from [W].
Manaflow Band grants you the mana sustain you need to stay in lane as long as possible so that you're able to effectively use your passive and abuse item power-spikes.
Transcendence's mid-game CDR is massively powerful on a teamfight orientend champion such as Ornn. The extra CDR means more CC, more shielding, and more damage.