Gold stacking and lane sustain.
Creative tools and rule bending
Swap Summoner Spells while out of combat. Swapping to unique Summoner Spells will increase the rate at which you can make future swaps.
You get free boots at 10 min. but you cannot buy boots before then. These boots give additional MS. For each takedown you acquire the boots 30s sooner.
Get a free biscuit every 3 minutes, until 12 minutes. Biscuits heal and permanently increase your max mana.
Bonus MS towards nearby allies that are movement impaired or enemies that you impair movement on.
Durability and crowd control
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.
+5 Armor or 6 MR (match-up)
Unsealed Spellbook's overall utility grants you the ability to adapt to situations where you need more damage for a kill, or defensive power from being killed.
Magical Footwear allows you to double-down on that gold you're earning from Klepto and Coin by saving you a bunch of gold so that you're able to invest it into combat stats for the mid game.
Biscuit Delivery further empowers your ability to out-sustain your lane opponent and helps you survive in machups where you may take a lot of early game damage (Gnar/Rumble).
Approach Velocity synergizes incredibly well with Nasus' [W] to chase down and stick to your target.
Conditioning makes you into a massive mid game front line tank as it will scale well with any defensive items you buy and continuing scaling into the late game with your infinite scaling damage.
Nasus is a champion who lives and dies by his ability to sustain with his passive. Revitalize massively empower that healing in the mid game where you'll be able to out-duel most other champions.