This Path of Exile 2 Mercenary leveling guide details optimal skills, support gems, passive skills, and item choices for a smooth progression to the endgame. While the Mercenary class is generally easy to level, strategic skill selection and itemization are key to maximizing efficiency.
Optimal Skills and Support Gems:
Early-game success hinges on Fragmentation Shot (effective close-range, multi-target damage) and Permafrost Shot (freezing for added Fragmentation Shot damage). As you progress, a grenade-focused build becomes significantly stronger.
The image below illustrates key skill gems and their ideal support gems. Use available gems until you acquire the recommended ones. Consider using a Lesser Jeweller's Orb to add support gem sockets to your key skills (Explosive Grenade, Explosive Shot, Gas Grenade).

| Skill Gem | Useful Support Gems |
|---|---|
| Explosive Shot | Ignition, Magnified Effect, Pierce |
| Gas Grenade | Scattershot, Fire Penetration, Inspiration |
| Ripwire Ballista | Ruthless |
| Explosive Grenade | Fire Infusion, Primal Armament, Magnified Effect |
| Oil Grenade | Ignition, Magnified Effect |
| Flash Grenade | Overpower |
| Galvanic Shards | Lightning Infusion, Pierce |
| Glacial Bolt | Fortress |
| Herald of Ash | Clarity, Vitality |

Essential Passive Skill Tree Nodes:
Prioritize Cluster Bombs, Repeating Explosives, and Iron Reflexes on the Mercenary Passive Skill Tree. These significantly enhance grenade damage and mitigate the drawbacks of the Sorcery Ward Ascendancy skill (the recommended Ascendancy for leveling). Also seek out nodes offering Cooldown Reduction, Projectile & Grenade Damage, and Area of Effect. Crossbow-related nodes and Armor/Evasion are secondary priorities.

Itemization and Stat Priorities:
Focus on upgrading your Crossbow first. Prioritize items with Dexterity, Strength, Armor, Evasion, Elemental Resistances (excluding Chaos), Physical and Elemental Damage, Mana on Hit, and Resistances. Rarity of Items, Movement Speed, and Attack Speed are beneficial but less critical. A Bombard Crossbow significantly boosts grenade projectile count.

This comprehensive strategy ensures a smooth and powerful leveling experience for your Mercenary in Path of Exile 2. Remember to adapt based on available items and your playstyle.