"Every 30 seconds, summon two Solus Probes that gain +100% (+100% per stack) damage per ally on your team." Yellow boss item dropped by Solus Control Unit. Summons two laser-firing Solus Probes (Quiet Probe red, Delighted Probe green) with 4x normal health and +300 hidden armor vs AoE attacks. Probe damage scales with every ally visible on your HUD column. With just the two probes alive, they start at 2x base damage since they count each other. Respawn every 30 seconds if killed. Not usable by Engineer turrets.
Drop source
Solus Control Unit
Probes summoned
2 (4 w/ Swarms)
Min damage
2x (probes count each other)
AoE armor
+300 (25% dmg taken)
How Empathy Cores Works
Probe damage scales with every ally visible on your left HUD column. Every ally counts: drones, turrets, other players, Beetle Guards from Queen's Gland, Aurelionite from Halcyon Seed, ghosts from Happiest Mask, Col. Droneman from Spare Drone Parts, Defense Nucleus Alpha Constructs. The two probes themselves count toward each other's damage. With only the 2 probes and no other allies, each probe deals 2x base damage since the other probe is counted as an ally.
The probes count each other but not the player who holds the item. Your character does not count as an ally toward the damage bonus. Everything else on your HUD ally column does. In a solo run with just the two probes, they each start at 2x damage. Add one drone and they each jump to 3x. Add five drones and they hit 7x.
Probes have +300 hidden armor against AoE, taking only 25% of AoE damage. Regular Solus Probes are fragile. These probes are not. 4x health plus massive AoE damage reduction means they survive sustained combat on most stages. They do die to targeted single-hit effects, but area-of-effect boss attacks and mass enemy fire barely scratch them. This lets them stay active and dealing damage for most of a fight.
Probes respawn every 30 seconds when killed, unless the ally cap is reached. The ally cap is around 16-20 total allies. If you have too many drones and other summons, dead probes cannot respawn until the count drops below the threshold. Plan your drone army to stay below the cap so probes always have a respawn slot. This becomes a real concern with Engineer turrets + drones + beetle guards all active simultaneously.
Stacking Empathy Cores has a known bug beyond the first stack. The item description says +100% per stack, meaning a second Empathy Cores should give probes +200% per ally instead of +100%. Due to a bug, stacks beyond the first do not properly increase the per-stack damage multiplier. In practice, one Empathy Cores is usually enough - focus on building more allies to increase probe damage rather than stacking the item.
Engineer turrets cannot receive Empathy Cores. It is blacklisted from Engineer turret inventories along with Queen's Gland. However, Engineer is still a strong survivor with Empathy Cores since his turrets count as allies and scale probe damage, even though they cannot hold the item themselves.
Probe Damage by Ally Count
Total allies
Example setup
Probe damage
Notes
2
Just the 2 probes
2x base
Probes count each other
4
Probes + 2 drones
4x base
Each drone adds 100%
7
Probes + 5 drones
7x base
Solid mid-run setup
12
Probes + 10 allies
12x base
Full drone army
4 probes
Artifact of Swarms
3x base (start)
4 probes count each other
Every ally on your HUD adds +100% probe damage. The return on each ally is linear - there is no diminishing return. Going from 7 allies to 8 allies gives the same +100% bonus as going from 2 to 3. Stack as many allies as the cap allows. The cap is the only limiting factor.
Best Survivors
Engineer
S Tier
Two turrets count as allies immediately, starting probes at 4x damage from the moment they spawn. Engineer naturally wants to be stationary while turrets fight, which also keeps probes near enemies. Empathy Cores cannot be held by turrets, but the turrets themselves scale probe damage. The combination of turrets plus any purchased drones makes Engineer the strongest Empathy Cores host in the game.
Captain
S Tier
Captain's passive Defensive Microbots protect nearby drones from projectiles, keeping the ally count stable. He can also call in Strike Drones with his Orbital Probe. His drone-first playstyle naturally accumulates allies fast. With Spare Drone Parts and Empathy Cores, Captain becomes the drone army commander the item was designed for.
MUL-T
A Tier
MUL-T's high HP lets him absorb damage while drones and probes do the work. His Retool lets him hold Spare Drone Parts alongside another equipment. High base damage means purchased drones scale well on him. Solid choice for a passive drone army build where MUL-T tanks while the probes and drones shred.
REX
A Tier
REX's slowing and rooting skills keep enemies near the probes long enough to take significant laser damage. His playstyle naturally involves staying back while plants and allies deal damage. Queen's Gland Beetle Guards gain additional value when REX keeps enemies slowed inside the probe engagement zone.
Key Synergies
Spare Drone Parts is the defining Empathy Cores partner. It gives probes a chain gun, missiles, and attack speed even though the augmentations are invisible on the probe models. Col. Droneman spawned by Spare Drone Parts counts as an ally, adding another +100% probe damage. Every purchased drone also benefits from Spare Drone Parts buffs. Together the two items turn an already strong drone build into a full damage ecosystem.
Queen's Gland Beetle Guards count as allies and scale probe damage. Each Beetle Guard is one more ally adding +100% to both probes. With multiple Queen's Gland stacks, Beetle Guards respawn regularly and can cap out your ally column quickly. On survivors who want a passive army, Queen's Gland plus Empathy Cores means probes scale even between drone purchases.
Happiest Mask ghosts count as allies for the duration they are active. Happiest Mask has a 7% chance on kill to spawn a ghost of the killed enemy with 1500% damage for 30 seconds. While that ghost is alive, it is on your HUD column and counts as an ally for probe damage. Against large packs, multiple ghosts can be active simultaneously, temporarily spiking probe damage by 2-4x or more.
Halcyon Seed Aurelionite counts as an ally during teleporter events. Aurelionite is an enormous powerful ally that appears during the teleporter event. It counts toward probe damage for the duration it is active. Combined with a full drone fleet, teleporter boss fights become the point where probes hit their peak damage output.
Artifact of Swarms doubles probes to 4, starting them at 3x damage minimum. With Swarms active, Empathy Cores spawns 4 probes instead of 2. All 4 count each other, so they start at 4x damage with no other allies. With a full drone fleet the damage output is absurd. Swarms also doubles all enemy spawns, making ally damage scaling more valuable since more enemies means more opportunities for damage.
Watch the ally cap - probes cannot respawn above it. The cap is around 16-20 allies. With Engineer turrets, multiple drones, Beetle Guards, ghosts, and Aurelionite all active, you can hit the cap. Dead probes will not respawn until slots free up. Do not over-build your army to the point where losing a probe during combat keeps it out of the fight permanently.
Frequently Asked Questions
What does Empathy Cores do in Risk of Rain 2?
Empathy Cores is a yellow boss item that summons two Solus Probes (Quiet Probe and Delighted Probe). The probes attack enemies with laser beams and gain +100% damage for every ally on your team. With just the two probes alive, they each start at 2x damage since they count each other. Every drone, turret, other player, Beetle Guard, ghost, or other HUD ally adds another +100%. Probes have 4x normal health and massive AoE damage reduction, and respawn every 30 seconds if killed.
What counts as an ally for Empathy Cores?
Anything visible on the left HUD ally column counts. This includes: the two probes themselves (toward each other), purchased drones of all types, Engineer turrets, other players in multiplayer, Beetle Guards from Queen's Gland, Aurelionite from Halcyon Seed, ghosts from Happiest Mask, Col. Droneman from Spare Drone Parts, and Defense Nucleus Alpha Constructs. The player holding the item does not count toward their own probes' damage.
Should you stack Empathy Cores?
Generally no. There is a known bug where stacks beyond the first do not properly apply the per-stack damage increase. In practice, one Empathy Cores is enough. Instead of stacking the item, focus on building more allies - more drones, Queen's Gland stacks, and other summons - to increase probe damage linearly without relying on the buggy stacking behavior.
Does Empathy Cores work with Engineer?
Yes, and Engineer is one of the best survivors for it. Engineer's turrets cannot hold Empathy Cores (it is blacklisted), but the turrets themselves count as allies and add +100% probe damage each. With two turrets active from the start, probes immediately operate at 4x damage. Adding purchased drones on top pushes them further. Engineer is the strongest Empathy Cores host due to passive ally generation from turrets.
What happens if you hit the ally cap with Empathy Cores?
If your total ally count hits the cap (around 16-20), dead probes cannot respawn. They will remain dead until another ally dies and frees up a slot. To avoid this, keep your total drone and summon count below the cap so probes always have a respawn slot available after being killed in combat.
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