Nasus should focus on safe full clears and avoid early fights to reach his scaling breakpoint against Gragas's medium early pressure.
Prioritize controlled river vision to contest Scuttle and prevent Gragas from leveraging his strong gank threat and objective control.
This matchup favors Nasus's late-game scaling juggernaut strength over Gragas's mid-game burst and utility.
Jungle Plan
Prioritize efficient jungle clears to reach level 6 and stack (Q) before looking for counter-ganks on Gragas's early gank attempts.
Use vision to track Gragas's first clear and be ready to counter-gank when he commits with (E) and (R).
Focus on securing early dragon vision and setups, then leverage your scaling to pressure side objectives and force Gragas into reactive plays.
Danger windows
Be cautious during early clears when health is low and smite is down, as Gragas can force fights here.
Avoid isolated river fights before you have vision control and lane priority due to (E) engage and (R) displacement.
Watch for Gragas's early gank timings using (E) to catch you before level 6 and your ultimate durability.
Early game
Start with a full clear to hit level 4 safely before contesting river or camps.
Avoid early invades unless Gragas is spotted on the opposite side and your lanes have priority.
Contest first Scuttle only if nearby lanes can assist and you have smite advantage to deny Gragas objective control.
Power spikes
Level 6 unlocks (R) for Nasus, greatly increasing durability and threat in extended fights; use this to survive Gragas's burst and punish prolonged engagements.
High (Q) stack threshold turns Nasus into a potent duelist; pressure side lanes once you reach this to force Gragas to respond.
Respect Gragas's level 6 (R) displacement by avoiding clustered fights before your ultimate is ready.
Win conditions
Convert superior scaling and high (Q) stacks into side-lane pressure that forces Gragas to split attention.
Use vision control around dragon and Rift Herald to deny Gragas's objective setups and force fights on your terms.
Track Gragas's pathing to leverage counter-gank potential and punish overextensions with your durable slows and extended fights.
Tip: For Nasus vs Gragas, read overview, trading pattern, and danger windows first for a fast Jungle lane check.