A half-robot, half-plant survivor who uses HP as a resource to cast powerful skills. REX's core tension is spending health to deal damage then recovering it through healing skills. Mastering this loop gives REX exceptional sustained self-healing, but losing control of it can quickly end a run. REX is the slowest survivor in the game and has no movement skills.
Never take Transcendence, Wake of Vultures, or any item that converts HP to shields on REX. His HP-cost skills drain actual health, not shields. Shields cannot be recovered by REX's healing. Shield-replacing items permanently cripple his self-sustain loop.
REX's skills fall into two categories: free skills (DIRECTIVE: Inject, DIRECTIVE: Disperse, DIRECTIVE: Drill) that cost nothing, and HP-cost skills (Seed Barrage, Bramble Volley, Tangling Growth) that spend a percentage of current HP. The game loop is cycling between spending HP on damage skills and recovering it through healing skills.
REX is unlocked by completing the Power Plant challenge. This requires safely carrying a Fuel Array from your starting Escape Pod all the way to the Broken Robot in Abyssal Depths (Stage 4). Any survivor can attempt this - you do not need REX.
At the very start of a run, turn around from your starting position and find the Escape Pod. Pick up the Fuel Array from the back of it. This is your equipment slot item.
Warning: do not fall below 50% HP while carrying the Fuel Array or it detonates, destroying it and likely killing you. Play carefully through Stages 1-3.
Reach Stage 4: Abyssal Depths. Note: Abyssal Depths is one of the two possible Stage 4 maps alongside Siren's Call. If you get Siren's Call, you must loop to try again.
In Abyssal Depths, find the Broken Robot on the upper platforms near the center of the map.
Interact with the Broken Robot while holding the Fuel Array to repair it. This completes the Power Plant challenge and unlocks REX permanently.
Play on Drizzle to reduce incoming damage. Engineer with turrets or Captain work well - both can deal with threats from a distance, reducing the chance of taking burst damage that drops you below 50% HP. The Fuel Array takes your equipment slot, so you play the entire unlock run without any equipment item.
REX's item priorities center on max HP (to increase the absolute HP value per percentage cost), healing amplification (to make skills recover more HP per hit), and movement speed (his only survivability tool since he has no dodge or mobility skills). Rejuvenation Rack is his single most impactful item.
Increases max HP (+40) and base regen (+1.6/s). Both benefits scale REX's HP-based skill economy - more max HP means each percentage-cost skill drains less total health, and higher regen recovers HP faster between uses.
Doubles all healing received. REX's Tangling Growth, Bramble Volley, and DIRECTIVE: Inject all heal HP. Rejuvenation Rack doubles every healing tick from these skills, dramatically improving REX's self-sustain loop.
Permanently increases max HP by 1 per kill, up to +100. More max HP directly increases how much HP REX can spend on abilities before becoming vulnerable. Stack early for a compounding benefit through the run.
Killing an enemy ignites nearby enemies. Tangling Growth roots enemies together in tight groups - when one dies to the combined damage, Gasoline ignites the rest for chain kills across the rooted cluster.
Explosion on kill within 12m. Rooted enemy groups from Tangling Growth die close together, meaning each kill triggers Will-o'-the-wisp in the center of the cluster and hits multiple other rooted targets simultaneously.
Enemies with 4+ debuffs take 50% more damage. Natural Toxins (Weaken), Tangling Growth (root), and DIRECTIVE: Harvest (inject) each apply debuffs innately. REX needs only 2 additional debuff sources to activate Death Mark reliably.
REX is the slowest survivor in the game with no movement skills. Movement speed is his only way to create distance from threats and reposition between Tangling Growth plants. Stack this early and often.
Attack speed increases DIRECTIVE: Inject's fire rate, generating more healing ticks from the third syringe per second. Also speeds up Seed Barrage's mortar fire and makes DIRECTIVE: Disperse's knockback more frequent.
REX's core loop against groups: throw Tangling Growth to root enemies together, follow with Seed Barrage mortars onto the rooted cluster, and use DIRECTIVE: Inject to heal from the third syringe between Seed Barrage spends. If HP drops critically low, Tangling Growth's healing from multiple roots can recover significant HP rapidly.
Secondary: Seed Barrage is default and generally stronger than DIRECTIVE: Drill for burst. Utility: Bramble Volley once unlocked - the HP cost is recovered when hitting multiple enemies, making it both damage and healing simultaneously. Special: Tangling Growth - keep default. It is REX's most powerful skill and the foundation of his kit. DIRECTIVE: Harvest is better against single high-HP targets.
Inject animation cancel: Firing Seed Barrage immediately after the third DIRECTIVE: Inject syringe cancels the end-lag animation, letting you fire Inject again sooner. This speeds up healing and damage cycling but costs HP per cancel.
Upward mobility with Disperse: Both DIRECTIVE: Disperse and Bramble Volley can be aimed downward to launch REX significantly upward, similar to a jump. REX is the slowest survivor with no movement skills - use this consistently to reach elevated positions and escape dangerous ground-level situations.
Tangling Growth range: Tangling Growth has truly infinite range. Fire it across the entire map at enemies you cannot reach otherwise. The healing from rooted enemies continues even after they die, so a successful root on a large group can recover significant HP over several seconds.
HP management: The 15% Seed Barrage cost is based on current HP, not max HP. The lower your HP, the cheaper each Seed Barrage is in absolute terms. REX becomes progressively cheaper to use at low HP, but also closer to death - finding the right operating range is the core skill of playing REX.
Complete the Power Plant challenge by picking up the Fuel Array from your starting Escape Pod and carrying it safely to the Broken Robot in Abyssal Depths (Stage 4). Do not fall below 50% HP while carrying the Fuel Array or it explodes. Any survivor can attempt this.
Never take Transcendence, Wake of Vultures, Silence Between Two Strikes, or any item that converts HP into regenerating shields. REX's HP-cost skills drain actual health, not shields, and his healing skills only recover HP. Shield items permanently break his self-sustain loop and make HP-cost skills unrecoverable.
REX is strong in the mid to late game once items accumulate. His biggest weakness is the early game when HP pools are small and one bad Seed Barrage spam can end a run. Once Rejuvenation Rack and Titanic Knurl stack up, REX becomes nearly unkillable through his own healing loop while dealing sustained high damage. He requires more active HP management than most survivors.
Seed Barrage costs 15% of REX's current HP per use, Bramble Volley costs 20%, and Tangling Growth costs 25%. These costs are percentage-based - at 100 HP, Seed Barrage costs 15 HP. At 50 HP, it costs 7.5 HP. HP-cost skills can bring REX to 1 HP but cannot kill him directly. The healing from Tangling Growth, Bramble Volley, and DIRECTIVE: Inject's third shot recovers these costs when used correctly.
Tangling Growth is generally stronger since it works on groups, heals from every rooted enemy, and has infinite range. DIRECTIVE: Harvest is better against single high-HP enemies (bosses, elites) where Tangling Growth only roots one target. Many players run Tangling Growth for group content and wish they had Harvest for boss phases - Tangling Growth usually wins overall.