S-TIER | BUILD MERCENARY INFINITE BURN OIL GRENADE (@jungroan) | SEASON 4

Build Overview

Oil Grenade is a build that clears entire screens with a single button, with damage that scales infinitely. The core interaction relies on a unique property of Incinerate and Flame Breath: the ignites generated by these spells stack indefinitely. The burning ground created by Oil Grenade can inherit this infinite stacking property if the target is already ignited by one of these stacking ignites. The result is a build that trivializes all content in the game.

Popularized during Season 4 notably by Chinese content creators, this Witchhunter build leverages the ascendancy to obtain Sorcery Ward as the main defensive layer, providing around 8,000 ward on maps that protects against all damage types. Combined with high evasion and deflection, the character is remarkably resilient while dealing virtually unlimited damage.

One of the most interesting aspects is the use of Weapon Master on the passive tree, which allows exploiting nearly 70 weapon set passives split between the crossbow (base damage, AoE, grenade cooldown recovery) and the staff (Flammability multipliers and ignite multipliers). It’s like playing with 150 to 170 passive points.

Build Strengths

• Infinite damage: Thanks to the Incinerate + Oil Grenade interaction, ignites stack indefinitely. Even in endgame, jungroan uses four utility supports rather than damage supports, such is the power level.
• Exceptional league start: No unique is required. The build works from level 31 with simply Incinerate and Oil Grenade. It trivializes all content as soon as these two gems are equipped.
• Solid defenses: Sorcery Ward (~8,000 ward), 24,000 evasion, 50% deflection. Unlike energy shield, the Sorcery Ward recharge cannot be interrupted.
• Screenwide clear: The massive AoE of Oil Grenade combined with Encroaching Ground and Magnified Area covers entire screens in a single throw.
• Class flexibility: The build can be played on any class, not just Witchhunter. Ranger, Monk, Huntress, Chronomancers with grenades, or even Titan with life stacking are all viable.

Build Weaknesses

• Sensitivity to stray damage sources: You must use Elemental Focus on all skills that deal damage except Incinerate, and avoid any thorns damage on gear, otherwise the infinite ignite interaction breaks.
• Degenerations: Even though jungroan doesn’t find them problematic thanks to ignite immunity and life recoup, damage over time can sometimes require using a life flask.
• Ground effects and performance: Mirage Archer generates additional ground effects that can cause lag, which is not ideal in intensive mapping.

Gem Setup by Step

This build offers 1 progression step from leveling to the final build. Select a step to see the corresponding gem setup.

Default

Default

11 skills • 52 gems

Tir à l'arbalèteCrossbow Shot

Égide magiqueSorcery Ward

Orbe solaireSolar Orb

Tir explosifExplosive Shot

Sensibilité aux élémentsElemental Weakness

IncinérationIncinerate

Oil Grenade

Archer mirageMirage Archer

Danseur du ventWind Dancer

Grenade assourdissanteFlash Grenade

Éclats galvaniquesGalvanic Shards

Recommended Equipment

• Staff (Weapon Set 2): Searing Touch is used for Ignite Proliferation, increased damage, Flammability magnitude, and ignite magnitude. It is not mandatory however: any staff works.
• Body Armour: Hyrri’s Ire doubles the value of Sorcery Ward by doubling evasion. It is the only optional unique that jungroan truly recommends, for its exceptional defensive synergy.
• Helmet (optional): Viper with the nearby effect is an interesting option for powerful nearby nodes like Tactical Retreat. Sandstorm Visage is an alternative to apply Crit Weakness to enemies.
• Crossbow (Weapon Set 1): An accessible craft. Look for % physical damage tier 3+, use an Essence of Abrasion for flat physical, then gain phys as fire. For suffixes, Dextral Crystallization and Perfect Essence of Battle guarantee +all attack skills.
• Gloves: Prioritize deflection equal to evasion, then evasion and resistances.
• Boots: Movement speed, life, rarity, resistances.
• Rings and Amulet: Resistances and rarity. The ideal amulet is +3, rarity and evasion (craft via Greater Essence of Opulence).

Gameplay Tips

• Rotation: Switch to Weapon Set 2 (staff), cast Incinerate once (the first tick is enough), then switch back to Set 1 and spam Oil Grenade. As long as the burning ground from the grenades touches the burning ground from Incinerate, the infinite ignites will propagate.
• Elemental Focus is mandatory: This support MUST be linked to every skill that deals damage except Incinerate. This includes Wind Dancer and Mirage Archer. Without it, parasitic ignites break the infinite interaction.
• No thorns: Check your equipment (especially belt and body armour) to avoid any thorns damage that could generate unwanted ignites.
• Leveling: Play grenade until level 31, then equip Incinerate and Oil Grenade (level 9 gems). The build trivializes all content from that point on.
• Gem Enthusiast: Balance 10 green supports (movement speed) and 10 red supports (life + ignite immunity if majority red). This balance applies per weapon swap.

The infinite ignite interaction explained

The core of this build relies on a particular property of Incinerate and Flame Breath: their ignites stack indefinitely instead of replacing each other. In practice, each tick of Incinerate adds a new ignite stack to the target, and these stacks never expire as long as the spell keeps hitting.

The interaction becomes truly powerful when Oil Grenade enters the picture. The burning ground created by Oil Grenade (or Oil Barrage) can inherit this infinite stacking property, provided the target is already affected by an ignite from Incinerate or Flame Breath. The two patches of burning ground must overlap for the propagation to work. That is why high AoE and Skill Effect Duration are so important: they increase the size and duration of the ground, making it easier to connect the two zones.

There is however a critical trap: any other ignite source from the player can break this interaction. That is why Elemental Focus is mandatory on all offensive skills except Incinerate, and why thorns damage on equipment must be avoided.

Weapon Master and the double passive tree

One of the most interesting mechanics of this build is the use of Weapon Master on the passive tree. This keystone allows different passives depending on the active weapon set, effectively providing a double passive tree with nearly 70 weapon set passives in total.

Weapon Set 1 (crossbow) focuses on three axes: grenade cooldown recovery and associated grenade nodes, area of effect to maximize burning ground coverage, and defensive stats such as evasion and movement speed. jungroan notes he does not take Volatile Grenades because with Short Fuse 2 (which is a « less detonation time »), the reduction of grenade detonation time is not additive with the « less ».

Weapon Set 2 (staff) is the caster setup dedicated to Incinerate and Elemental Weakness. Priority stats are Flammability magnitude and ignite magnitude. The build uses the multipliers from Incinerate (Flammability magnitude, ignite duration, ignite magnitude) combined with the base damage of Oil Grenade from Set 1. It is this synergy between the two sets that makes the build so powerful.

Sorcery Ward and the build’s defense

Sorcery Ward is often considered an inferior version of Energy Shield, but jungroan argues it is actually extremely powerful, even superior in certain cases. The character walks around with roughly 8,000 ward during mapping, and this protection works against all damage types, not just elemental damage.

Hyrri’s Ire doubles the value of Sorcery Ward by doubling the character’s evasion (provided you have not been hit recently). Combining this with 24,000 evasion and approximately 50% deflection chance makes the character highly resilient to both heavy hits and multiple hits.

The major advantage of Sorcery Ward over Energy Shield is that its recharge cannot be interrupted. As soon as the character starts taking damage, the ward regeneration countdown starts automatically, regardless of subsequent hits. For damage over time, ignite immunity via Crystallized Immunities on the passive tree makes most DoTs negligible.

From Nothing jewels and optimization

The « From Nothing » jewels are an important part of optimizing this build. jungroan primarily uses Hollow Palm Technique, and for good reason: the Skill Effect Duration it provides acts as a damage multiplier for this build. It increases the duration of Oil Grenade’s burning ground, meaning more ticks of infinite ignite on bosses, and during mapping it allows you to throw a grenade on one side of the map, sprint to the other side, and wait an extra second or two before needing to reconnect with another grenade.

Altered Brain Chemistry is also recommended as it works with Lavangas (a permanent but very low mana flask). Heightened Rider is valued for movement speed and especially projectile speed, which prevents premature detonations caused by Short Fuse.

For rare jewels, jungroan looks for area of effect, mana on kill, ignite magnitude, Flammability magnitude, elemental damage, evasion, crossbow damage, cooldown recovery, and skill effect duration.

Passive Tree