I Runners are orange humanoid Infested Corpus crewmen that sprint towards a player and explode. Since update 8.3, they can knock the player down for a few seconds. Because of this, it is recommended that players should kill them first. If a player cannot escape a Runner's blast, he/she can roll to avoid being knocked down or stunned. They can easily stunlock or cause prolonged knockdowns resulting in the players death.
Runners killed by gunfire may cause them to explode on death, which can be problematic for teammates who were close by. Killing a Runner with a bolt firing or melee weapon, however, will prevent them from self-destructing.
When using heavy melee weapons (i.e. Fragor), rapidly meleeing makes the animation difficult to interrupt by runners and chargers because of the weapon's momentum.
Runners will still explode when you are near them with Shade's cloaking ability activated. This can deal damage to you and possibly reveal your position by knocking you out of cloaking range. Abilities such as Loki's Invisibility and Ash's Smokescreen also do not seem to consistently prevent a Runner from detonating when you are nearby. However, they will not pursue you if you run out of detonation range while invisible.
Among the light Infested, Runners are the least dangerous to Defense objectives as the shields on said objectives will often regenerate between Runner explosions and each Runner can only attack once. However, a barrage of detonations can easily paralyze a Tenno while Leapers and Chargers tear the objective to shreds.
Runners, along with Leapers, are immune to stunning effects including weapons that have innate stun capabilities.
When the runner's exploding animation starts, it is frozen in space and cannot move around until it explodes or dies. Sometimes it will stop before it explodes and reverse the animation, if cloaked and moving out of it's range.