You know that you can't obtain or get a XT Mission or a XT until you reach generalissimo?

Do you know how rare a XT is? I tried on the test server to get a XT. It failed miserably, and left me with about 500000 crystals (I started with 1000000). Don't waste too much crystal on trying to get a XT! Plus, you have to kill 99999 tanks or earn 999999 XP which is a lot.