Rammus should leverage his high gank threat and mobility to pressure lanes early, avoiding extended farming against Jarvan IV who clears faster and has stronger early objective control.
Prioritize punishing Jarvan IV's early gank attempts by tracking his pathing and preparing counter-ganks or safe pathing away from his engage angles.
Focus on scaling into a tanky anti-AD frontline role to outlast Jarvan IV's mid-game engage and control teamfights with taunts and knockups.
Jungle Plan
Use early ganks with (Q) and (E) to punish Jarvan IV's overextended lanes before he can snowball from his level 2-3 engage power spike.
Track Jarvan IV's first clear and path to counter-gank his ganks or invade when his engage combo is unavailable.
Prioritize river control and dragon setups when Jarvan IV commits to lanes, using your taunt and knockups to secure objectives or force him out.
Danger windows
Be wary of Jarvan IV's early level 2-3 gank pressure from fog of war with (E)+(Q) combo, especially on pushed or flashless lanes.
Avoid isolated river fights or objective contests when Jarvan IV's ultimate (R) is ready, as it can trap and lockdown targets.
Exercise caution during low-health clears or forced smite fights where Jarvan IV's engage and objective control can decisively punish you.
Early game
Start with a three or four-camp clear aimed at lanes that are overextended or lack flash to maximize early gank impact.
Contest first Scuttle only if nearby lanes have priority and Jarvan IV's engage combo (E)+(Q) is on cooldown.
Avoid direct early invades unless Jarvan IV is spotted on the opposite side or his engage cooldowns are down to reduce risk from his level 2-3 pressure.
Power spikes
Respect Jarvan IV's level 2-3 power spike when (E)+(Q) engage is available; avoid isolated fights during this window.
Punish Jarvan IV's engage cooldowns by invading or forcing fights when (E)+(Q) is down.
Leverage Rammus's scaling into late game as a tanky anti-AD frontline with impactful taunts and knockups to control teamfights against Jarvan IV's medium scaling.
Win conditions
Convert early gank pressure into lane priority for your teammates to secure first dragon and Rift Herald.
Use your mobility and taunt to counter-gank and punish Jarvan IV's overextensions or cooldown windows.
Scale into a tanky frontline that locks down Jarvan IV's carries with taunts and disrupts his engage, denying him effective teamfight initiation.
Tip: For Rammus vs Jarvan IV, read overview, trading pattern, and danger windows first for a fast Jungle lane check.
