The Rubat kyber crystal can be found on Phemis in the Corellian sector, as Suns of Fortune sector book mentions briefly, and of course it is the destination of the adventure Hidden Depths (GM’s kit.)
The only issue, which already has been addressed on the FFG forums by perceptive fans, is that the Rubat crystal has not been given stats of its own.
It’s to be treated as a Ilum crystal. This is hardly satisfactory for anyone who’s played KOTOR (and I’m sure others too.) Kyber crystals should differ, even if the variations are only slight. No two types should be the same.
Some suggestions on the forum tweak the Ilum a bit, making the Rubat somewhat weaker in terms of upgrades – namely removing 1 or 2 Damage upgrade mods.
Presented below is my suggestion:
Found on Phemis in the Corellian sector, these kyber crystals can be found in deep caves often treacherous and inhabited by strange, dark creatures. When attuned to and placed in a lightsaber the blade is sharpened in appearance and definition.
Base Modifiers: Installing this crystal changes a lightsaber’s base damage to 6 and critical rating to 3, and the lightsaber gains the Breach 1 and Sunder weapon qualities. If the crystal is removed, the lightsaber loses those qualities and reverts to its previous base damage and critical rating.
Modifications: 3 Damage +1 Mod, 2 Decrease the weapon’s critical rating by 1 to a minimum of 1 Mod, 1 Item Quality (Accurate +1) Mod, 1 Item Quality (Vicious +1) Mod.
Hard Points Required: 2
Cost/Rarity: 10,500 credits/10 (R)