ルビー

The most versatile gem in the game, producing three different effects depending on where you socket it.

• Weapon socket: Chance on hit to grant lifesteal (Chipped: 7% lifesteal).
• Armor socket: Amplifies all healing received (Chipped: +10%).
• Backpack slot: Once per battle, after a 5-second delay, deals magic damage to the enemy with 150% lifesteal attached (Chipped: 4 damage).

• Lifesteal heals for "actual damage dealt x lifesteal %." The calculation is based on damage after enemy shields have been applied, not raw damage.
• The healing amp effect applies multiplicatively to every healing source — Regeneration, food, lifesteal, potions, and so on. However, Goobert-style "Regen consumption" effects reportedly do not benefit from it.
• Backpack damage is magic-typed and partially bypasses enemy shields.
• The backpack effect only triggers once per battle. Stacking multiple Rubies in your backpack does not grant additional triggers.
• Weapon sockets and armor sockets are tracked independently, so multiple Rubies embedded in the same weapon or armor roll their effects separately.

Ruby is the most generically useful of the five gems — the classic "just grab Ruby if you're unsure" pick. It adapts to both offensive and defensive boards and never goes dead in any class. Weapon Ruby grants permanent effective HP through lifesteal, while armor Ruby doubles down on the scaling of any healing-focused build.

On a weapon, the multiplicative scaling with damage per hit is the core strength. A high-damage, slow weapon like Double Axe, Doom Greatsword, or Blood Scythe returns far more HP per lifesteal trigger than a low-damage dagger. Conversely, low-damage multi-hit weapons (Falcon Blade, Shortbow) lean on proc volume for consistency rather than big individual heals.

Perfect Ruby (35% lifesteal) represents roughly a 5x leap in per-hit healing compared to the lower tiers, which makes the Flawless-to-Perfect promotion a genuine game-changer. Budget for that upgrade path from the early rounds.

The backpack effect — a single burst of 150% lifesteal magic damage — is limited, but it functions as a one-time damage supplement in aggressive early-rotation builds that race the opponent down in the first 5 seconds. Because all backpack Rubies trigger simultaneously on the same 1-per-battle timer, filling your pack with them is not recommended.

• Slot Chipped Ruby (1G) into a weapon in the early game as a cost-efficient durability base. Epic can be crafted from four 1G copies, so the cost-to-value ratio is superb.
• Sockets on Blood Scythe and Death Scythe (weapons with native lifesteal) add to Ruby's % additively — a top priority for Reaper.
• In healing builds, slot into armor to amplify Regen and food healing. The multiplicative stacking with Gluttony Amulet is particularly strong.
• Two same-rarity copies craft one tier up. The Flawless-to-Perfect jump (two 8G copies) is a match-defining investment.
• Treat backpack Ruby as "early-game insurance" only — don't expect it to scale into mid- or late-game.
• Lifesteal is wasted at full HP, so Ruby shines paired with self-damage builds (blood weapons) or overhealing sinks.

Reaper Blood Scythe Dual-Wield

Equip two Death Scythes and socket Perfect or Flawless Ruby into each. The weapon's native lifesteal adds to Ruby's % for over 50% total lifesteal. Pestilence Flask reinforces poison damage, with Fly Amanita adding more poison stacks. One Perfect Ruby plus two Flawless copies is the ideal gear spread.

Adventurer Offense-Defense Hybrid

Fill your backpack with three to four Chipped/Flawed Rubies so the opening Regen trigger feeds Thornbloom, converting it into lifesteal + thorns. Also slot a Regular Ruby into your weapon for a second lifesteal layer. Extend the thorns synergy via relic access.

Mage Armor Ruby Healing Cycle

Balance Wand plus a Flawless Ruby in your armor. The 3 HP every 3.3s heal becomes 3.75 HP with +25% amp. Healing Herb's Regen is also amplified, maximizing attrition tempo over long matches.

• Lifesteal is wasted at full HP. In overkill-damage builds, you'll miss much of the value. Pair Ruby with intentional self-damage or overheal sinks like Goobert to solve this.
• Backpack Ruby triggers once per battle only. Stacking gems in the backpack does not add more procs.
• If your opponent runs armor Amethyst (-45% healing at Perfect), your lifesteal is also attenuated. Don't over-invest in Ruby in an anti-heal meta.
• Chipped Ruby (1G) is ridiculously cost-efficient early, but holding onto one into late game leaves you under-powered. Keep promoting via crafting.
• Below Flawless, Ruby is sometimes outclassed by Sapphire or Topaz. If other gems are already established, there is no need to force more Rubies into the build.

This item feeds into the following upgrade paths.