The Best REX Build for Risk of Rain 2: Mastering the Self-Sustain Loop

Mastering REX’s HP-Cost Mechanic

REX is one of the most distinct survivors in Risk of Rain 2. Unlike other characters who rely on cooldown management, REX operates on a high-risk, high-reward system where his HP is a primary resource. His offensive skills, such as Seed Barrage, consume a percentage of your current health to deal massive damage.

The core of playing REX effectively is maintaining a balance. You are not meant to stay at 100% HP, but you must ensure your healing output keeps pace with your damage output. If you spam your HP-costing abilities without securing hits with your healing skills (like the primary "Inject" or the special "Tangling Growth"), you will quickly find yourself at dangerously low health. Community guides emphasize that your goal is not to avoid health loss entirely, but to cycle it efficiently: spend HP to destroy high-priority targets, then heal off clusters of smaller enemies.

The Best Items for a REX Build

Because REX’s gameplay loop relies on specific interactions between HP and healing, his item priorities differ significantly from other survivors.

Healing and Survivability

• Rejuvenation Rack: This is arguably the "God Tier" item for REX. Since it doubles all healing received, it effectively turns your self-sustain loop into an unstoppable force. Finding one can completely change the momentum of a run.
• Tougher Times: Since you are constantly draining your own health, having a chance to block incoming damage is invaluable. It reduces the stress on your healing cycle.
• Harvester's Scythe: Once you can reach high critical hit chances, this becomes a reliable source of healing. It allows you to heal even while spamming your secondary abilities.
• Topaz Brooch: This item is excellent for early-game survivability. The barrier it provides acts as a buffer, allowing you to use your HP-costing skills without dipping into your actual health pool immediately.

Utility and Scaling

• Soldier’s Syringe: REX’s primary attack, "Inject," is your bread-and-butter healing source. Increasing your attack speed allows you to fire more syringes, which means more healing ticks per second.
• Paul’s Goat Hoof: REX is notoriously slow and lacks built-in mobility skills. Stacking movement speed items is non-negotiable to help you reposition and avoid getting cornered by elites.
• Infusion / Titanic Knurl: These items increase your maximum HP. Because REX’s skill costs are percentage-based (e.g., 15% of current HP), having a larger health pool gives you more "room" to cast abilities before you reach critical levels.

Warning

Items to Avoid Never pick up Transcendence, Wake of Vultures, or any item that converts HP into shields. REX’s HP-costing skills drain your actual health. If your health is converted to shields, you cannot heal that "health" back, effectively killing your self-sustain loop and making it impossible to manage your resources.

Recommended Skill Loadout

While REX’s default kit is powerful, his alternative skills offer different tactical advantages depending on your playstyle.

• Secondary Ability: Seed Barrage is generally considered the superior choice over the alternative, Directive: Drill. Seed Barrage offers high burst damage with a very short cooldown. While it costs HP, the damage output is often worth the trade-off.
• Utility Ability: Bramble Volley is a strong upgrade over the default Disperse. It deals significant damage and provides healing based on the number of enemies hit, making it both an offensive and defensive tool.
• Special Ability: Tangling Growth remains the go-to for most players. Its ability to root enemies and provide healing over time is essential for crowd control. Directive: Harvest is a niche alternative that works better against single, high-HP bosses, but it lacks the group-clearing potential of Tangling Growth.

Pro Tips for Playing REX

• Animation Canceling: You can significantly increase your fire rate by firing Seed Barrage immediately after the third syringe of Inject. This cancels the end-lag animation of the primary attack, allowing you to cycle your healing and damage output much faster.
• Use Disperse/Bramble Volley for Mobility: You can aim your utility skill (Disperse or Bramble Volley) downward while jumping to launch yourself into the air. This serves as REX's only real mobility option, allowing you to reach high ledges or escape ground-level hazards.
• Manage Your HP Targets: Don't waste your HP-costing skills on singular, weak enemies. Use your primary attack to clear out small mobs and save your heavy-hitting, HP-draining skills for elites and bosses where the healing from "Tangling Growth" can be maximized.

How to Unlock REX

If you have not yet unlocked REX, you must complete the "Power Plant" challenge.

1. Find the Fuel Array: At the start of a run, look behind your escape pod to find the Fuel Array.
2. The Challenge: You must carry this item to the Abyssal Depths (Stage 4) and insert it into the Broken Robot.
3. The Catch: The Fuel Array takes up your equipment slot, and it will explode if your HP drops below 50%. You must play carefully and prioritize healing to ensure you don't take a fatal hit while carrying it.

FAQ

Is REX good in the late game? Yes. While REX can be challenging in the early game due to small HP pools, he becomes a powerhouse in the mid-to-late game once you accumulate healing items like Rejuvenation Rack and attack speed buffs.

Which special should I use: Tangling Growth or Directive: Harvest? Tangling Growth is generally better for most runs because it provides area-of-effect crowd control and reliable healing. Directive: Harvest is only recommended if you struggle specifically with single-target boss encounters.

Does REX's healing work on shields? No. REX’s healing skills only restore actual health. This is why you must avoid items that convert health to shields.