Almost everyone in my guild, when they reached the Spires of Arak, chose the Brewery Garrison Outpost, which rewards (among other things) a passive 20% increase to XP while in the zone. Pretty good deal, right?
Well, maybe not. After a bit of research I chose the Trading Post building, which allows you to summon an NPC called “Honest Jim” every 10 minutes while in the Spires of Arak. What’s so good about Honest Jim you might ask? Well, in addition to some nice potions and other consumables (a 28 slot bag for 2200 gold), Honest Jim will sell an item called Inactive Apexis Guardian, which allows you to add a follower named Ziri’ak to your garrison.
Ziri’ak is an Apexis Guardian, and the reason why I’m glad I got him is because he comes to your garrison as level 99. You are eligible to enter the Spires of Arak at level 96, so that means you’ll have a high level follower for your garrison.
There are benefits (and some hindrances) to this. First, it means that you have 1 heavy handed follower to send on some missions, thereby slightly increasing the success rate. However, adding this guy to your garrison opens up level 99 missions, meaning you have fewer missions to choose from where you’ll have a 100% success rate. That being said, I didn’t notice myself failing too many missions after I added this follower to my garrison.