League of Legends Reforged Rune: Grasp of the Undying
Grasp of the Undying

Entering combat generates 1 stack every second for the next 3 seconds. Additional stacks may be generated by re-entering combat after 2 seconds. After reaching 4 stacks, your next basic attack on-hit within 6 seconds against an enemy champion consumes all stacks to deal (3.5% for Melee / 2.1% for Ranged) of your maximum health as bonus magic damage, heal for (1.7% for Melee / 1.02% for Ranged) of your maximum health, and permanently grant (5 for Melee / 3 for Ranged) bonus health. The empowered attack duration refreshes whenever going in combat.

So according to lol wiki grasp of the undying requires players to leave combat and then re-enter in order to gain the last stack to proc the rune. Is that really the case?
Only ranged on-hit to procs.(ex:tiamat deadmans plate are excluded).