Olaf needs to pressure Gnar early and deny his safe scaling by forcing extended melee fights where Olaf's sustain and (R) crowd control immunity shine.
Olaf's high early agency and lane pressure allow him to control the lane pace and prevent Gnar from safely stacking Rage or using terrain for mega form engages.
This is a snowball vs scale matchup; Olaf must snowball early advantages to prevent Gnar from reaching impactful mega form windows.
Trading pattern
Start trades by landing (Q) to slow and chase Gnar, then extend fights using (W), (E) true damage, and commit with (R) only when Gnar cannot fully disengage.
Punish Gnar when his (E) hop is down in mini form by forcing extended fights and denying his kiting.
Avoid trading when (Q) misses or (R) is unavailable, as Gnar can kite and disengage effectively otherwise.
Danger windows
Be cautious when Gnar's Rage is near mega form and he can engage with (E) hop or (R) wall stun near terrain.
Avoid fighting when (R) is down, as Olaf loses crowd control immunity and becomes vulnerable to Gnar's hard CC.
Respect (W) stun in mega form; do not commit if you cannot avoid or outplay it during all-ins.
Early game
Use level 1-5 to aggressively land (Q) axes and pick them up to maintain chase and pressure Gnar's fragile mini form.
Avoid missing (Q) as it greatly reduces Olaf's ability to stick and trade effectively against Gnar's kiting.
Use (W) shield and lifesteal to sustain through poke and prepare for level 6 all-ins.
Power spikes
At level 6, use (R) to gain crowd control immunity and force straight-line fights ignoring Gnar's mega form CC; commit only if you can keep hitting him.
After your first fighter item, pressure side lanes and extend fights with increased damage and durability to punish Gnar's missed disengages.
Respect Gnar's level 6 mega form when he has Rage near full and terrain angles for (R) wall stun; avoid fighting during his mega form windows unless you have clear advantage.
Win conditions
Win by landing repeated (Q) slows and forcing extended melee fights where Olaf's sustain and (R) crowd control immunity overpower Gnar's kiting.
Deny Gnar safe Rage buildup and mega form engages by pressuring the wave and forcing fights before he can transform.
Use side-lane pressure after first item spike to create kill opportunities and snowball advantage into mid-game control.
Tip: For Olaf vs Gnar, read overview, trading pattern, and danger windows first for a fast Top lane check.