I went through the Aghs Lab game files to check what unused items there might be hidden in them and found something that seems rather out of place:

An item upgrade for Falcon Blade, which comes with a rather unique passive proc.

Video: https://youtu.be/n55La8Q72MQ

Considering the item’s magician rank related name, it reminds me of the other hidden item upgrade (Grandmaster’s Glaive) that I covered a year ago.

Archmage's Naginata:

Price: 2500g(?)2626g¹

Components: Falcon Blade (1125g) + Oblivion Staff (1500g) + Recipe (1g)

Stats²: 200 hp, 2.05 mana regen, 27 attack damage, 12 int, 30 atk speed

Passive: no name

Effect: Upon attack land has an 18% chance to advance owner’s spell cooldowns by 2% of their respective current values.

The passive itself has no name and the item has neither a description, nor visible stats, nor icon (I gave it Diff2’s icon), but you can find out what it does by taking a look at the game files and by testing of course.

Archmage's Naginata’s passive effect:

The effect should be able to proc on any attack³, regardless of target, as long as it is not evaded or disjointed.

Effectively the game checks all your spells (doesnt affect items) that are currently on cooldown and upon proc advances them all by 2% of their respective current cooldowns.

Spells, that are currently on cooldown, will cool down slightly faster by skipping parts of their cooldowns upon proc.

It does nothing to spells that are currently off cooldown, since it does not use cooldown reduction.

Example #1: Techies’ Minefield Sign is currently on a 360s cooldown and his Blast Off is currently on a 35s cooldown.

Upon effect proc, Minefield Sign’s current cooldown will be reduced by 7.2 seconds and Blast Off’s current cooldown will be reduced by 0.7 seconds.

Example #2: Techies’ Minefield Sign is currently on a 100s cooldown and his Blast Off is currently on a 10s cooldown.

Upon effect proc, Minefield Sign’s current cooldown will be reduced by 2 seconds and Blast Off’s current cooldown will be reduced by 0.2 seconds.

Item game file location and elaborating more stuff:

Location: C:Program Files (x86)Steamsteamappscommondota 2 betagamedota_addonsaghanimscriptsnpcnpc_items_custom.txt

Original values: https://imgur.com/a/1AFu5Fi

Imported values: https://imgur.com/a/a0q1zOq

The weird thing about this item is that it is the only item upgrade in the Aghs Lab item files, other than the Vault Bloodstone (which is just a modified Bloodstone), so I will disregard that one.

Additionally some of its stats were initially nulled, it was set to be not purchasable and strangely marked as a neutral item, despite requiring two regular items.

It is also the only item in the Aghs Lab item files which does not import a BaseClass for its functionality, which I assume means it will work out of the box when imported into regular non-Aghs Lab dota (and indeed it does).

Footnotes:

Footnote ¹: The game lists the price as 2500g, but its components yield a combined cost of 2626g instead.

Footnote 2: Half of its in-game stats (mana regen, damage, health) were initially set to zero, I filled those in by combining the components’ stats instead.

Footnote 3: I only tested attacking enemy heroes, buildings and neutrals. It likely works on any attack target, but I did not test every single unit type in the game.