The following support gems are recommendations by GGG as listed in-game, and do not necessarily reflect optimal combinations or the views of the wiki.
Gem tier
Support gems
I
Magnified Area IMagnified Area ISupport, AoE Tier: 1 Cost & Reservation Multiplier: 130%Support Requirements: +5 IntSupports any skill with an area of effect, making it larger.Supported Skills have 35% increased Area of EffectPlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
Multishot IMultishot ISupport, Projectile Tier: 1Support Requirements: +5 DexSupports Projectile skills, making them fire extra Projectiles. Also lowers Attack and Cast speed of supported skills, as well as lessening their damage.Supported Skills deal 35% less Damage Supported Skills fire 2 additional Projectiles Supported Skills have 20% less Skill SpeedPlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
II
Adhesive Grenades IAdhesive Grenades ISupport, Grenade Tier: 2Support Requirements: +5 DexSupports Grenade Skills. Grenades from Supported Skills do not bounce, instead halting movement where they intially land, but doing lower damage when they detonate.Supported Grenade Skills stop where they initially land Supported Grenade Skills deal 10% less DamagePlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
Font of BloodFont of BloodSupport, Totem Tier: 2Support Requirements: +5 StrSupports Skills which create Totems. Totems created by supported Skills generate a Font of Blood which will Leech Life to Allies within it.Totems created by Supported Skills create a Blood Font with a radius of 4 metres Allies in Blood Fonts Leech Life equal to 12% of Physical Damage dealt by Supported TotemPlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
Urgent Totems IUrgent Totems ISupport, Totem Tier: 2Support Requirements: +5 StrSupports Skills which create Totems, causing those Skills to place Totems much more quickly.Supported Skills have 80% increased Totem Placement speedPlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
III
Greatwood IGreatwood ISupport, Totem Tier: 3 Cost & Reservation Multiplier: 115%Support Requirements: +5 StrSupports Skills which create Totems, limiting their active Totem count to one but granting significant benefits for supported Totems based on what their TotemLimit would have been without this restriction. Does not Support Skills used by Minions.Supported Skills can only have one active Totem TotemLimit instead grants 5% increased Area of Effect for Totems per Limit to Supported Skills, up to 20% TotemLimit instead grants 10% more Totem Damage per Limit to Supported Skills, up to 40% TotemLimit instead grants 10% more Totem Life per Limit to Supported Skills, up to 40%Place into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
IV
PayloadPayloadSupport, Grenade Tier: 4Support Requirements: +5 DexSupports Skills which fire Grenades, giving fired Grenades a chance to activate again, but lengthening their cooldowns.Supported Skills have 70% reduced Cooldown Recovery Rate Grenades fired by Supported Skills have 50% chance to activate a second timePlace into a Skill's Support Gem socket in the Skills Panel to apply its effects to that Skill. You cannot have multiple Support Gems of the same Category socketed within one Skill.
V
Item acquisition
Mortar Cannon has restrictions on where or how it can drop.