Dragon Age: The Veilguard

During the Treviso main quest, “Sea of Blood,” in chapter 4, you’ll head to The Ossuary to save Lucanis.

About midway through said quest, you’ll face off against a boss on your way to Lucanis, The Fabricator. Once you defeat said boss, you’ll unlock a chest which has the Glaciate rune inside of it.

Once you’ve looted it, head to the Character tab in the main menu and head to the right of the screen to the three slots that surround Solas’ dagger. Click on a slot, select the rune you just unlocked and equip it. Once you do, the ‘Rune for Improvement’ achievement will unlock.