It can be unlocked by finding and defeating it in "Sunken Tombs", where the crate containing it is sometimes located, in the top right corner of the map.
Maul an enemy for 120% damage. The target is poisoned for 24% damage per second.
Spit toxic bile for 220% damage, stunning enemies in a line for 1 second.
Secrete poisonous sludge for 2 seconds. Speeds up allies, while slowing and hurting enemies for 90% damage
Release a deadly disease, poisoning enemies for 100% damage per second. The contagion spreads to two targets after 1 second.
Release a deadly disease, poisoning enemies for 100% damage per second. The contagion spreads to two targets after 1 second. If an enemy is killed by Pandemic, you are healed.
- The poison applied in Festering Wounds is stackable.
- Caustic Sludge has a 17 second Cooldown, but the trail itself will last for nearly 15 seconds, meaning that by the time it dissipates, Acrid will be ready to spread another trail shortly. Spam it as often as possible, as it slows enemies down and speeds allies up, making it great not only for combat, but for escaping as well.
- Try to spread Caustic Sludge in as wide an area as possible, avoiding bumpy, uneven terrain as much as possible.
- Hanging on a rope after spreading Caustic Sludge is a safe way to kill a big group of enemies, as this will keep them grouped and most of them can not reach the character.
- The Caustic Sludge can easily take out a group of imps holding a reward, as the Acrid can spray the ground directly next to the statue, summon them, and they'll die easily and quickly, granting an easy and painless reward.
- Epidemic will spread on contact with other mobs, as well as attempt to jump to others close enough on the screen. It can multiply itself and do devastating damage to groups, and can go through walls. Note that it won't return to a previously infected enemy.
- As with any melee user, Acrid is a little flimsy and should make use of items such as the Hermit's Scarf, Tough Times, Colossal Knurl, Mysterious Vial, Bitter Root, Infusion, and Guardian's Heart for the sake of survivability.
- Also, as with any melee user, Acrid is always in the thick of the fight whenever he wishes to do damage. Thus, he benefits from passive damage items like Frost Relic, Barbed Wire, Tesla Coil, Burning Witness, Fireman's Boots, Plasma Chain and Chargefield Generator. With all of these together, the bulk of his damage will come simply from proximity.
- Items that add status effects or damage over time stack well with Acrid's inherent abilities in this regard, such as Thallium, Rusty Knife, Toxic Worm, and Shattering Justice.
- Due to the stacking nature of Festering Wounds, it's a good idea to get Soldier's Syringes and Energy Cells whenever possible. To synergize with this, melee users like Acrid may find the Hyper-Threader, Leeching Seed, Laser Turbine and Heaven Cracker to all be of use with his high attack speed, and any on-hit effects for that matter can only help.
- Stun items help Acrid maintain momentum, avoid damage and keep enemies in his Caustic Sludge. To bolster this, gather Tasers, Concussion Grenades, Prison Shackles, Spikestrip and Permafrost.
- As a class that must move around in the fray, and works well with hit-and-run strategies, items such as the Red Whip, Paul's Goat Hoof, Hopoo Feather, Photon Jetpack, and Rusty Jetpack can help him quite a lot. Items that increase movement speed can help him spread Caustic Sludge much further, and jetpacks and hopoo feathers can allow the player to repeatedly hop above a placed area of sludge to lure enemies into it without putting themself in harm's way.
- Acrid benefits from on-death effects like Will-o'-the-wisp, Happiest Mask, Gasoline and Ceremonial Dagger as, within an area of sludge, they can help him gain very fast momentum and eliminate a large group quickly, bolstering his Burning Witness, Chargefield Generator and Frost Relic in turn.
- Meat Nugget, Filial Imprinting and Interstellar Desk Plant can be helpful as they drop buffs or heals in the sludge while the player is fighting large groups, allowing them to stay in their sludged area longer.
- The Unstable Watch is very good for doing large amounts of damage to bosses.
- At low health, it is a smart strategy to try to get Epidemic on one enemy and flee.
- Epidemic can pass through terrain, both on its initial attack and as it spreads. The initial attack also has unlimited range.
- Epidemic's first hit on mobs (as well when it passes to another enemies) is treated as a hit, allowing on hit items a chance to proc.
- As with other melee characters, Heaven Cracker gives unlimited range to Acrid's basic attack when it procs. However, Festering Wounds is not applied to enemies hit by it.
- Acrid is still the only playable class that can be fought in-game by the player.
- Acrid’s name is synonymous with acid, harshness and sharpness, linking in with his nature and acidic abilities.