Ghost

Ghost, sometimes called Ghost Walk, is a summoner spell that boosts your movement speed for several seconds and lets you move freely through other units. It rewards sustained chasing and repositioning rather than the single instant of an escape blink.

It suits champions who fight for a long time and want to stick to targets or kite away, including many bruisers and a few hyper-mobile carries. Compared to Flash, Ghost covers more total distance but cannot cross walls and is much easier for an alert enemy to react to, so the two spells solve different problems.