Detonation Orb

Stats

Values as the League of Legends Wiki's item data lists them, for every mode; the data doesn't state their units.

Effects

• The Bomb (unique): Dealing ability damage against enemy champions marks them for 3 seconds, storing 20% of the post-mitigation damage you deal to them, increased to 25% if they are immobilize. Subsequent ability damage dealt to a marked target refreshes their mark. Once the mark expires, it detonates to deal true damage equal to the amount stored against the target. If a mark would deal lethal damage to the target, it detonates immediately.³

• Build Karthus with Detonation Orb, Diamond-Tipped Spear and It's Killing Time to deal heavy damage at the start of a round.⁵

• Detonation Orb is a distributed item exclusive to Arena and can only be obtained as a Prismatic item.⁶¹⁴ Patch unknown
• Detonation Orb can stack marks on a target until they explode and die.⁷

Earlier formats

• Having Detonation Orb on both teammates can deal enough damage to execute an enemy who still has high health.¹⁰ 8x2 duos
• Detonation Orb can stack Nasus's Q damage and pop champions at full health.¹¹ 8x2 duos
• With Detonation Orb, burn items or high ability power can help store enough damage for an automatic execute.¹² 8x2 duos
• Mana changed from 400 to 600 and Damage Store changed from 25/30% to 20/25% in patch 25.06.¹³ 8x2 duos
• Detonation Orb's damage counted as item damage after patch 14.17.¹⁴ 8x2 duos