Ignite

Ignite is an offensive summoner spell that sets an enemy champion on fire, dealing true damage over five seconds and applying Grievous Wounds, which cuts the target's healing. The damage scales with your level, so it stays relevant from the early laning phase into the mid game.

It is the classic aggressive pick for solo laners and assassins who want kill pressure, and for supports who play to engage. Ignite is most famous for securing kills on low-health targets who would otherwise escape, and the healing reduction makes it strong against champions who rely on sustain to survive a fight.