Underboss 4-Mark Team Stacking Guide

The Underboss exotic SMG applies a mark on hit that can stack up to four times across multiple agents using the weapon. Each additional mark beyond your own increases amplified damage by 5 percent, reaching up to 35 percent bonus with full team coordination. Master difficulty Climax mission guarantees the first-time drop.

Underboss is an exotic SMG introduced in Into the Dark designed explicitly for coordinated team play. Solo agents receive value from their own mark but miss the primary amplified damage bonus that requires multiple team members wielding Underboss simultaneously.

Acquisition: Master difficulty Climax mission guarantees the first-time drop. Subsequent drops follow standard exotic loot tables from targeted farming. Prioritize Master Climax completion early in the season for guaranteed acquisition.

SMG range limitations require close-to-mid engagement positioning. Team compositions must account for shared positioning requirements where all four Underboss agents maintain fire on the same target within SMG effective range.

The Underboss talent applies marks independently per agent. Each agent mark persists on the target and stacks with marks from other agents using Underboss, creating the 4-mark team synergy.

Each Underboss hit applies one mark to the target. Marks persist for a duration refresher on subsequent hits. Maximum four marks exist on a target, one per team member wielding Underboss.

Your own mark provides a base amplified damage bonus. Each additional mark from an ally adds 5 percent amplified damage. With four agents each applying one mark, total amplified damage reaches 35 percent above baseline.

Marks apply to all damage sources against the marked target, not just Underboss damage. This means your team DPS agent running a different weapon still benefits from the amplified damage bonus on marked targets.

Mark application requires hit confirmation. Missed shots, blocked hits, and damage to non-target enemies do not apply marks. Accuracy and positioning ensure consistent mark uptime on priority targets.

Optimal team: four agents each equipped with Underboss SMG. All four focus fire on the same priority target to maintain four active marks. Coordinate target callouts through voice communication.

Alternative team: three Underboss agents plus one dedicated skill DPS or tank. The non-Underboss agent benefits from 3-mark amplified damage (30 percent bonus) while providing role coverage the SMG loadout lacks.

Build each Underboss for crit chance and crit damage to maximize SMG output during mark maintenance. SMG talents like Close and Personal or Devastator supplement mark damage contribution.

Positioning protocol: designate a team leader who calls target priority. All Underboss agents collapse on called target within SMG range. After target elimination, immediately transition to the next called target maintaining mark stack discipline.

For Climax mission specifically: four-Underboss teams trivialize boss armor phases when all agents maintain mark uptime during armor break windows. Schedule Master Climax runs with pre-organized four-Underboss groups for fastest clear times.

Base mark from self: approximately 15 percent amplified damage depending on exact talent values.

Each ally mark: plus 5 percent amplified damage.

One agent solo: approximately 15 percent amplified damage on marked targets.

Two agents: approximately 20 percent amplified damage.

Three agents: approximately 25 percent amplified damage.

Four agents: approximately 35 percent amplified damage on marked targets from all damage sources.

This multiplicative bonus applies to weapon damage, skill damage, and status damage against the marked target. Combined with group buffs from Caduceus healing sustain and damage buffs, four-mark teams achieve exceptional time-to-kill on elite and boss enemies.

Master Climax mission: primary acquisition and showcase content for four-mark stacking. Boss encounters with extended damage phases maximize mark uptime value.

Escalation high tiers: mark amplification accelerates elite elimination where time pressure from mutators demands fast kills. Four-Underboss Escalation groups require dedicated healer support from Caduceus builds.

Raid encounters: sustained boss damage phases benefit from mark stacking when all agents maintain SMG range positioning. Coordinate with tank agents who hold boss aggro while four Underboss agents maintain fire.

Not recommended for: Toxic DZ solo farming, open world solo content, or PvP where SMG range disadvantage and mark coordination difficulty reduce effectiveness. Deploy Underboss teams exclusively in organized PvE group content.

Underboss mod optimization mirrors standard SMG setup: crit chance and crit damage priorities on optical, muzzle, underbarrel, and magazine slots. The mark amplification bonus multiplies all damage, making crit investments on Underboss itself compound with the team-wide amplified damage buff for multiplicative rather than additive gains.

Communication discipline separates successful four-mark teams from groups that leave damage on the table. Assign one agent as mark caller who announces target switches. All four agents fire exclusively on called targets until elimination before switching. Split targeting across multiple enemies prevents mark stacking from reaching four active marks on any single target.

If your group lacks four Underboss copies, three-mark setups with 25 percent amplified damage still outperform solo Underboss usage significantly. Recruit a fourth Underboss holder through LFG communities focused on Climax mission and Escalation progression during Into the Dark launch window when Underboss acquisition is highest across the player population.

Inspect your Underboss roll after acquisition from Master Climax. Recalibrate for Critical Hit Chance and Critical Hit Damage before first use in organized content. A well-rolled Underboss with high crit stats maintains mark uptime through faster kills, indirectly improving team damage by reducing the time enemies survive without active marks between target transitions.