The things that can benefit you as a raider from garrisons are mainly:
getting gear from Missions and professions,
gaining Apexis Crystal, and a few other minor benefits.
The gear produced by your Garrison comes from missions rewards, work orders, and crafting gear for your character through profession buildings.
Gaining Apexis Crystaloccurs through mission rewards, almost all non-small building work orders, dailies offered at your Garrison, and Garrison invasions.
- Your own gear-related profession building: If you have a profession that makes gear, by having a profession building related to your existing profession, you will effectively halve the time it takes to make items, since you will have twice the daily cooldown.
- Profession buildings for which you do not have the profession:you can also craft gear for yourself from profession buildings without having the associated profession, albeit at a much slower rate and a smaller selection of items.
- Salvage Yard: One of the ways to get gear from your garrison for raiding is by sending your followers off on missions that reward gear (see a list of missions that reward gearhere ) as well as missions that reward Caches from the Highmaul raid which also may contain gear. Missions that reward epic gear have an 630 item level requirement for your followers, and missions that reward epic raiding gear have an ilvl 645 requirement for your followers. Having the Salvage Yard Level 1 as a garrison building allows you to loot Crate of Salvage while completing missions. These can only be opened at your Salvage Yard Level 1 and have a chance to contain the items needed to upgrade your follower's gear. These items are fairly common from the Crate of Salvage. See a list of all the follower upgrade items here. In addition, when you level your Salvage Yard to 3, you may occasionally find gear for your own character in the Big Crate of Salvage.
- TheBarn provides some raiding benefit in the form of materials for upgrading crafted items and a chance at providing Savage Feast in the Barn Level 3's work orders. While you can cook personal 100 stat food, this is the only feast you can set out for your raid that provides 100 stat food.
- TheDwarven Bunker/War Mill provides a benefit to the above outlined description of gaining gear through missions because the work orders at the Dwarven Bunker Level 2 reward the weapons and armor used to increase your followers' item levels. These work orders open up at level 2. When you level your Bunker/War Mill to 3, you are granted one free Seal of Tempered Fate per week. This does not grant you an extra roll, just one of your 3 is free of charge. This may be a benefit to time-limited raiders, in addition to helping gear up your followers.