Each Clash Rune adds 40 item level, and the Nightmare shop sells the chest

What people say

The guides say there are two rune slots, that each rune adds 40 and that they come from regional quest chests; for the Elyos, from Verteron. Going to +1 never fails, and above that the rune can break: some guides say from +2, others from +3.

What happens

• The first rune took me from 959 to 999: exactly 40.
• I got the second one from the Nightmare shop: the Clash Rune Chest (Bound) costs 500 Phantasmal Fragments and contains 1 Clash Rune and 9 Clash Rune Enhance Scroll. With it, from 992 to 1,032.
• The rune is a “Special Rune”, item level 40: +0.5% PvE damage and survivability, 100 penetration, +1% combat speed and +1% multi-hit.
• I took both to +2 without either one breaking: from 1,040 to 1,044, one point per “+”.

On 9 October the Nightmare shop also had: Daevanion crystals at 300 (50 per character), Stigma Shard at 1,500 (35 per character), Soul Codex at 400 (5 a week), Soul Codex: Reset at 8,000, Amplify Stone fragments at 500, wings, appearances and boss statues.

What to do

If you’re missing a rune slot, your first Nightmare purchase is the chest. Then Daevanion crystals. With the runes at +2 I stopped: the leftover scrolls aren’t worth the risk of losing 40 in one go.