As with all Savior achievements you need to:
- visit striking locations (6) and delves (2)
- complete the area's main quest
- kill world bosses (2)
- complete quests (16)
Map-reference:
https://game-maps.com/ESO/Galen-Map.asp1. As for the striking locations you need to visit all
There is a total of six striking locales and two delves here. As for the striking locales (Windwrack Fort, The Telling Stone, Castle Tonnere, Glimmertarn, Clohaigh, Ivyhame), you visit most of them during the main quest - finish up the rest afterwards. When visiting the delves make sure to collect the skyshards and also do the related quests as you need to do some additional quests anyway for the "Galen Grand Adventurer" ingame-achievement which is a requirement for this chevo as well.
After visiting all delves and striking locales you are awarded with the in-game achievement "Galen Master Explorer".
2. Just follow the main questline, which also awards you the "Firesong Extinguisher" xbox achievement. Sidenote: it already nets you 8 of 16 quests that you need for this chevo, too.
3. There are two world-bosses here:
Optionally combine these kills with daily-quests for an additional reward-box. Killing these two bosses also awards you with the ingame-achievement "Defender of Galen".
4. After finishing the area's main questline you should only need a couple of more quests to reach 16 completed quests. After finishing up with this one you are awarded the ingame-achievement "Galen Grand Adventurer".