Rune · tier 4 · from floor 16
Thrum
Set in a weapon: +9% skill area. Set in an off-hand or armour: +6% swing speed.
Drops from floor 16 down.
What it adds
- Tier
- 4
- First floor
- 16
- In a weapon
- +9% skill area
- In an off-hand or armour
- +6% swing speed
- Smith’s price to empty
- 75 gold
The line counts once per socket it sits in: two Thrum runes in one weapon give twice +9% skill area. On the gear screen, tap a rune, then an empty socket. A set rune stays: the only way out is the Smith in town, who empties a socket for gold (30 for a tier 1 rune, up to 90 for tier 5) and destroys the rune; the socket stays, ready for another. A rune adds its weapon line in a weapon and its other line in an off-hand or armour.
Where it drops
A kill drops a rune 50% of the time for a boss, 6% for an elite and 0.4% for any other monster. Which rune it is depends on the floor: tier 1 runes drop from floor 1, tier 2 from 5, tier 3 from 10, tier 4 from 16 and tier 5 from 22, and among the tiers a floor allows each rune is weighted 32 at tier 1, 16 at tier 2, 8 at tier 3, 4 at tier 4 and 2 at tier 5, so a deeper tier never becomes common. Runes you carry are banked when you go home through a portal; a fall loses them with the items you carry. On floor 16, where it first can drop, 1.9% of the runes that drop are Thrum; deeper, the higher tiers join the draw and its share shrinks.
| Floors | Share of runes | Boss kill | Elite kill | Other kill |
|---|---|---|---|---|
| 16–21 | 1.9% | 1.0% | 0.12% | 0.008% (1 in 13,000) |
| 22 and deeper | 1.9% | 0.9% | 0.11% | 0.008% (1 in 13,250) |
“Share of runes” is the chance that a rune that drops is Thrum; the other columns multiply it by each kill’s chance of dropping a rune at all.
Inscriptions
Thrum is part of one inscription: Last Light (third of 3, for the Warrior). An inscription is cut when an item has exactly as many sockets as the inscription has runes, every socket filled, in the inscription’s order. A 3-socket chest with Brine and Quill in its first two sockets spells nothing: the count must match too. The inscription’s power works only for the hero it is cut for; on anyone else the item keeps its rune stats and the power sleeps.
Other runes
The other tier 4 rune is Marrow. All 14 are on the runes page.