This Path of Exile 2 Mercenary leveling guide outlines optimal skills, support gems, passive skills, and item choices for a smooth progression to the endgame. While Mercenaries are considered easy to level, strategic build choices are crucial for maximizing effectiveness.

Early Game Strategy: Initially, focus on Fragmentation Shot (effective close-range, multi-target) and Permafrost Shot (quick freezes, amplifying Fragmentation Shot damage). This approach mitigates the early-game weakness before unlocking powerful grenade skills.

Mid-to-Late Game Power Spike: The build's strength truly emerges with the unlock of grenades and Explosive Shot. This shifts the playstyle to a devastating grenade-based approach.

Core Leveling Skills and Support Gems:

Note: Use available support gems until acquiring the recommended ones. Utilize a Lesser Jeweller's Orb to add support gem sockets to key skills (Explosive Grenade, Explosive Shot, Gas Grenade).

Essential Passive Skill Tree Nodes: Prioritize Cluster Bombs (adds projectiles), Repeating Explosives (chance for double explosions), and Iron Reflexes (converts evasion to armor, countering Sorcery Ward's armor penalty). Also seek out nodes that boost cooldown reduction, projectile/grenade damage, and area of effect. Crossbow-related nodes and armor/evasion are secondary priorities, only addressed if necessary.

Itemization and Stat Priorities:

Focus on upgrading your Crossbow first. Prioritize items with:

• Dexterity
• Strength
• Armor
• Evasion
• Elemental Resistances (excluding Chaos)
• Increased Physical/Elemental Damage
• Attack Speed
• Mana/Life on Hit/Kill
• Item Rarity
• Movement Speed

A Bombard Crossbow is highly recommended, adding an extra grenade projectile.

The synergy between skills and the strategic passive skill tree choices, coupled with smart itemization, makes this a highly effective Mercenary leveling build in Path of Exile 2. Remember to adapt and adjust based on available gear and encountered challenges.