This guide seems to provide a fairly straightforward walkthrough (if a total pain to actually do).
- Obtain magenta crystal schematic from a world boss
- Belsavis boss drops +33 crit
- Hoth boss drops +33 endurance
- (maybe...all bosses might have a chance to randomly drop one of the three)
Obtain the materials. Most are easy (you get them from Crew Skills) except for the Magenta Adgean Crystal. In order to get that:
Get the "Refreshed and Sustained" buff from a "water thingy" in the Jundland area of Tatooine (north of Mos Anek) at about (470, -2047)
Go to Hoth, climb a mountain at (-993, 148) until you get a debuff ("Extreme Altitude") and the item Pure Shockfrozen Water in your inventory (don't drink it)
Head to Ilum, and around (-548, 36) there should be an item called "Depleted White Adgean Crystal". Clicking it will spawn a Force Ghost, a level 50 champion with 215 kHP who will turn anyone's ice cube into the magenta crystal after looting his corpse. A full group of 50s (4) is recommended. If you fail, you can reattempt so long as you still have the water.