Q: How do I make sure I am ready to upgrade my HQ level to 21 & 22? A: Make sure your current HQ level is 20. Also, upgrade your Supply, Steel and Tech Stockpiles at HQ Level 20 so that the resource caps are greater than the HQ upgrade requirements. Resources required to upgrade to HQ Level 21: 
Resources required to Upgrade to HQ Level 22: 
Q: What’s new at HQ levels 21 & 22? Why should I upgrade to new HQ levels? A: Upgrading the HQ levels will allow you to build more defence structures on your base, place more mines. You can level up most of the Buildings, Troops and Command Powers. Upgrading also unlocks a new Troop . Q: When is the new Troop unlocked and what is it called? A: We are very excited to introduce to you the Hunter MK.I. The new Troop is unlocked at HQ level 22 . It can be used for both offensive and defensive purposes. The Hunter MK.I can be trained on Rally Flags for defense and on Tarmacs for offensive purposes. 
Q: How does having Hunter MK.I Troops help in my battle? A: The Hunter MK.I are ground units. They can attack both air and ground enemy targets. The Hunter MK.I moves at lightning speed on the battlefield. It’s high rate of fire chain gun wipes out enemies quickly, allowing it to function as a good front-line unit. It’s secondary weapon also shoots down enemy projectiles fired at your Troops, thus protecting them from Artillery and Metal Rain fire. Use the Hunter MK.I in conjunction with other Troops to protect them. Q: How many Troops of Hunter MK.I can I have on my Tarmac? A: If you have a Tarmac at level 10, you can train up to 9 Hunter MK.I Troops. 
Q: Can I upgrade my Hunter MK.I? If yes, how do I do that? A: Upgrades for Hunter MK.I troops will be available soon. Q: What are the buildings that can be upgraded at HQ Levels 21 & 22? A: By upgrading to HQ Level 21, the following buildings can be upgraded to make them bigger, better and stronger:
- Supply Drop
- Supply Stockpile
- Steel Factory
- Steel Stockpile
- Tech Factory
- Tech Stockpile
- Oil Derrick
- Fuel Stockpile
- Guard Tower
- Domed Defense
- Artillery
- Patriot
- Railgun
- Metal Rain
- Research Agency
- Storage Bunker
- Weapons Command
- War Factory
By upgrading to HQ Level 22, the following buildings can be upgraded:
- Fuel Stockpile
- Guard Tower
- Domed Defense
- Artillery
- Patriot
- Railgun
- Metal Rain
- Research Agency
- Storage Bunker
- Weapons Command
- War Factory
- Alliance Building
- Walls
Also, you get to upgrade the War Factory recipes for the following: ● War Factory Upgrades at HQ Level 21:
- Stealth Generator
- Drone Hive
- Ion Cannon
● War Factory Upgrades at HQ Level 22:
- Stealth Generator
- Drone Hive
- Ion Cannon
In addition to the above, more Defensive Structures can be built once you upgrade to HQ Level 21 & 22 . ● Additional buildings unlocked at HQ 21:
- Metal Rain
- Patriot
- Shock Mines
● Additional buildings unlocked at HQ 22:
- Domed Defense
- Land Mines
Q. Can I also Upgrade my current Troops and Command Powers at HQ Levels 21 and 22? A: Yes, you can upgrade the Troops at the Tarmacs and upgrade the Command Powers at Research Agency. Q. Can I Donate the Hunter MK.I Troops to my Allies? A: Yes, you can donate the Hunter MK.I Troops.
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Empires & Allies Game GUIDE