Overview
This build makes one enormous Ignite and then refuses to let it die. Oil Grenade lays a burnable patch, a fully-channelled ten-stage Flameblast detonates it into a devastating burn, and every subsequent Oil Grenade carries that same Ignite forward into the next pack. Nothing about the clear depends on re-casting the expensive skill — the initial burn just keeps propagating.
Boss fights use the identical sequence at a slower tempo: drop oil under the target, channel Flameblast to full, and then spend the rest of the fight dodging while the Ignite ticks. It is a rare damage profile where the payoff is entirely front-loaded, leaving your attention free for mechanics.
Gemling Legionnaire supplies the scaling. Quality on gems translates into raw ignite output, and the build climbs steadily through gem levels, ignite magnitude and fire damage rather than through a shopping list of uniques. Cast on Elemental Ailment triggering Tornado fills the one gap the ground-based burn has — flying enemies that burning oil cannot reach.
Pros & Cons
Pros
- Zero mandatory uniques; progresses on entirely generic rare gear
- Very cheap to start and scales smoothly through gem quality and levels
- Ignite propagation via Oil Grenade makes mapping fast with minimal input
- Bosses are handled by one setup-and-dodge rotation instead of sustained uptime
- Defensively solid: large life pool, high armour, and armour modifiers that also apply to elemental damage
Cons
- Not playable from level one — the creator recommends levelling as Explosive Grenade or Permafrost Bolts and swapping around level 60
- Screen clutter is severe once Ignite, Tornado and grenades all overlap
- One hard build-breaker: any flat fire damage added to attacks anywhere on gear ruins the Oil Grenade ignite interaction
- The Cast on Elemental Ailment setup is Spirit-hungry and cannot be fitted immediately
- Uses a very stretched passive tree, which trades efficiency for jewel sockets
Key Skills
- Flameblast — the ten-stage payoff; Burgeon II, Considered Casting, Concentrated Area, Searing Flame II, Ignite III
- Oil Grenade — lays the burnable ground and spreads the Ignite; Short Fuse II, Elemental Focus, Multishot II, Nova Projectiles I, Encroaching Ground
- Cast on Elemental Ailment → Tornado — automatic extra clear, covers flying enemies the ground burn misses
- Arctic Armour — defensive layer with Cannibalism and Cooldown Recovery
- Mana Remnants — resource sustain with Remnant Potency I and Harmonic Remnants II
Gear & Anointments
The rare staff is the main offensive upgrade: level of all Fire Spell Skills, damage as extra fire, and increased spell damage, with flammability, ignite magnitude and fire damage as optional scalers. The crossbow only needs +5 to level of all Projectile Skills for Oil Grenade — everything else on it is irrelevant, except that added fire damage to attacks must be avoided. Armour pieces chase life, armour, elemental resistances and Spirit, and the armour-also-applies-to-elemental-damage modifier is especially valuable on helmet and gloves. Jewels want ignite magnitude and increased armour, and the stretched tree provides plenty of sockets for them. Morior Invictus is best-in-slot body armour (five-socket on a higher budget) but is strictly optional; Loreweave can outperform it with the right roll but is hard to find. Campaign bonus picks: stun threshold in Venom Crypts, global defences from Tribal Medicine, elemental resistances in Halls of the Dead, movement speed from Chimeral Boons. Two extra gem setups are run purely to reach four red and six green gems for the Gem-Studded ascendancy point.
Endgame Notes
The character transitions naturally into its endgame form after the level 60 swap — from there it is gem levels, ignite magnitude and armour. Mageblood and other high-end items fit but are never required.
Credits & Source
Build credited to Odealo. See the source video for the full build’s gameplay footage + voice commentary: Flameblast/Oil Grenade Gemling Legionnaire Build - PoE 2 0.5 Build Guide.