This spell can be used to save a life when low on health and under attack. It is commonly used to get an early first blood by healing oneself for more than one's opponent expects. It is also a skill used for "baiting", where you make your champion appear weaker than it actually is, to lure your enemies out of position or to get them to tower dive you. A similar baiting tactic is also commonly used with Barrier.
This summoner spell is considered by many to be vastly superior to Barrier for a number of reasons - the heal is permanent, affects two people instead of one, and gives a 30% speed boost to yourself and your ally. However, Barrier is not affected by Grievous Wounds, has a shorter cooldown, blocks more damage (against a single target), and can be used while you're still at full health (good against 100-to-0 burst).
Barrier will always negate 40% of Ignite's damage if it is activated while under the effect of Ignite for at least 2 seconds. Heal will always negate more damage than Barrier. Note that Heal will absorb a larger portion of Ignite's damage at lower levels.
The cooldown of this spell can be reduced by summoner spell cooldown reduction.
Summoner spell CDR
Base cooldown ▶
▼ Cooldown reduction
Heal and Ghost are the only usable summmoner spells in the basic tutorial.
A debuff is now placed on champions healed by Summoner Heal for 25 seconds. Subsequent Summoner Heals will have their effect diminished by 50% on allies with the debuff. Your Champion will still receive the full amount of the heal if cast by your Summoner.
Mender's Faith (mastery) now provides 10 × level bonus health on Summoner Heal from 75 flat bonus health and 10 seconds cooldown reduction.