Item upgrades +1 to +15

Every step from +0 to +15 with its jewels, zen and chance, and the Jewel of Ancient for ancient items.

The whole path#

Level	How	Chance	On failure
+0 → +6	Jewel of Bless, one per level	100 %	—
+6 → +9	Jewel of Soul, one per level	50 %, 75 % with Luck	+6 drops to +5; from +7 or +8 back to +0
+9 → +15	Chaos machine (below)	50–60 %, +25 % with Luck	The item is destroyed; an ancient item up to +13 loses one level instead

A Jewel of Soul also works on items below +6, at the same 50 %, but Bless is free of risk there.

Talk to the Chaos Goblin in Noria, put the item and the jewels into the machine and press Combine.

Upgrade	Item	Jewels	Zen	Chance	With Luck
+9 → +10	+9	1 Bless, 1 Soul, 1 Chaos	2,000,000	60 %	85 %
+10 → +11	+10	2 Bless, 2 Soul, 1 Chaos	4,000,000	60 %	85 %
+11 → +12	+11	3 Bless, 3 Soul, 1 Chaos	6,000,000	55 %	80 %
+12 → +13	+12	4 Bless, 4 Soul, 1 Chaos	8,000,000	55 %	80 %
+13 → +14	+13	5 Bless, 5 Soul, 1 Chaos	10,000,000	50 %	75 %
+14 → +15	+14	6 Bless, 6 Soul, 1 Chaos	12,000,000	50 %	75 %

Excellent and ancient items get 10 % less (an excellent +9 with Luck: 75 %).
On a failure the item and the jewels are gone. On a success the jewels are used up and the item keeps all its options.
Ancient items don't burn from +10 to +13. If the upgrade fails, the jewels and the zen are gone, but the ancient item stays in the machine one level lower: a +11 that fails becomes +10, a +9 that fails becomes +8. Excellent and normal items are still destroyed.
Wings take the same recipes.
Ancient items can't use the +13 → +14 and +14 → +15 rows. They have their own recipe with the Jewel of Ancient (below).

The Jewel of Ancient is our own jewel and the only way to take an ancient item past +13.

Upgrade	Put in the machine	Zen	Chance
Ancient +13 → +14	The ancient item +13, 1 Jewel of Ancient, 1 Jewel of Creation, 1 Jewel of Chaos, and an excellent item +9 to +15 with 3 or more excellent options	0	50 %, 60 % if the ancient item has Luck
Ancient +14 → +15	The same with the ancient item at +14	0	30 %, 40 % with Luck

The three jewels are used up either way.
On a success the excellent item is used up and the ancient item gains a level.
On a failure the ancient item keeps its level and the excellent item stays: only the jewels are lost.
Only the ancient item's Luck counts; the excellent item's doesn't.

A whole ancient set at +14 or +15 adds 5 or 10 % to your stats and a gold glow: see Ancient +14 and +15.

Where it comes from: the bosses of the Tier Maps drop it on tiers 4, 5 and 6, at 10 %, 20 % and 35 % a run.

Luck adds 25 % to every chaos machine upgrade and to Jewel of Soul, so a Luck item is the best base for +10 and up.
An item's options don't change with its level, only its damage or defense does. Upgrade the item whose options you want to keep for a long time.
Keep your +9 excellent items with 3 or more options: they are the second ingredient of the Jewel of Ancient recipe, and they come back if it fails.