Radiant Hextech Gunblade

radiant

Heal the lowest percent Health ally for 40% of damage dealt.

Source

Heal · to specific allies

A Heal restores Health to a unit.
Mana

Mana is the unit-level resource that gates ability casts.
Mana Regen

Mana Regen is a stat that trickles Mana into a unit every second on its own.
Ability Power

Ability Power (AP) scaling means an effect gets stronger when its holder stacks AP.
Attack Damage

Attack Damage (AD) scaling means an effect gets stronger when its holder stacks AD.
Omnivamp

Omnivamp heals a unit for a percentage of the damage it deals.
Targeting

Targeting is how a unit chooses what to attack or hit with an ability.