Lee Sin should leverage his very high early game pressure and mobility to force early river fights and invade before Rammus completes multiple full clears.
Prioritize disrupting Rammus's slower clear speed and low objective control by contesting Scuttle and river control aggressively to snowball lanes and deny his tempo.
Jungle Plan
Prioritize invading Rammus early when lanes have priority to force him off camps and deny his slower clear tempo.
Contest first Scuttle only if nearby lanes can move first to avoid risky isolated fights against his (Q) engage and (E) taunt.
Use successful ganks and counter-ganks to reset tempo and keep camps from falling behind, focusing on early dragon and Rift Herald setups to deny Rammus scaling.
Danger windows
Respect Rammus's early invade timing around his first 3-camp clear and possible cross-map ganks using (Q) and (E).
Avoid isolated river fights without vision or lane priority, as Rammus's engage and taunt can force unfavorable skirmishes.
Be cautious during low-health clears or forced smite fights where Rammus can capitalize on his tankiness and crowd control to win duels.
Early game
Start with a path that enables a strong level 3 invade or counter-invade, focusing on early river Scuttle control when nearby lanes have priority.
Avoid extended full clears early; mix camps with pressure to maintain tempo and apply early map pressure before Rammus can respond.
Use (Q) and (W) mobility to track and punish Rammus's pathing, especially when he attempts cross-map ganks or overextends on camps.
Power spikes
At level 3, Lee Sin gains full kit access, enabling strong dueling and invade potential; use this to force river fights and punish Rammus's slower clears.
At level 6, (R) kick allows isolation of priority targets and objective denial; use it to disrupt Rammus's access to dragon or Herald.
Respect Rammus's power spike when he reaches level 6 with (Q) rolling engage and (E) taunt, as he can punish overextended targets and initiate fights.
Win conditions
Convert early invade pressure and river control into objective setups by securing Scuttle, dragon, and Rift Herald before Rammus can contest.
Use Lee Sin's superior dueling and mobility to counter-jungle and punish Rammus's slower clear speed, denying him farm and scaling.
Leverage creative gank angles and (R) displacement to snowball lanes and maintain tempo before Rammus reaches his late-game tank power spike.
Tip: For Lee Sin vs Rammus, read overview, trading pattern, and danger windows first for a fast Jungle lane check.