The simplest way to get user_key ID and your Facebook. No need to cheat engine.
1. Open dragon city or monter legend = Google Chrome
2. Fully loaded waiting game
3. Right click in the white box to the left outside playing DC ( or MLG) -> View frame source
4. In the open source tab Ctr + F to find session (which is user_key 8 of which people need)
5. Ctrl + F to find the userid (which is User facebook)
Some find a clever hack that link, you can refer to it
-DC:
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[Only registered and activated users can see links. Click Here To Register...]
-MLG:
[Only registered and activated users can see links. Click Here To Register...]
-SE
[Only registered and activated users can see links. Click Here To Register...]