(adsbygoogle = window.adsbygoogle || []).push({}); Here is a list of tweaks that are compatible in ios8.
This is not my list, I'm only linking to this list as a reference for anyone who is wondering.
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This list is actually being constantly updated so be sure to check back every so often and see what else is compatible.

Just be careful when installing because you can put your iDevice in an infinite boot-loop.

That's why you install substrate

Tried that but after rebooting Idk what happens but my device stays on the white apple logo screen. -iPhone6

you have to hold down the +volume button as it boots and it will go into a kind of safemode where you can uninstall the bad tweak