Quick Travel / Taxi
For Republic players, this one’s going to be a really long run.
Find the Ice Ramp
Enter the Crystal Tunnel
Sneak Past the Creature
Killing the creature is part of another achievement on Ilum though.
Ilum Purple Mastery Datacron Guide
The Ilum Purple Mastery Datacron is located in the Eastern Ice Shelf map on Ilum grants Mastery +4 (it used to grant Willpower +4 before the stats changed).
The Ilum Purple datacron is in the tunnel in the northeast corner and is available to both Imperial and Republic players. Finding this datacron will give you a permanent stat boost of Mastery +4 to all your characters on your server, and will unlock the Galactic History 87: A Wayward Apprentice codex.
Ilum Mastery +4 Datacron (Both Factions)
Quicktravel: 
Republic Waystation / 
Imperial War Camp
Taxi: Republic Waystation / Imperial War Camp
Location: Eastern Ice Shelf - tunnel in the northeast corner
Difficulty: Easy - can walk right up to it
Codex: Galactic History 87: A Wayward Apprentice
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