Rules of Creation:
For basic creation, you can create any ability you find on forums/wikis/guides.
But I will exclude the possibility to create destructive abilities and revives, aswell as abilities that angle the game through phase shortening or flavour investigations.
For advanced ability creation, for example in events, the same rules will apply. Tho you will be able to create supervised, conditional versions of above restricted abilities.
A restriction is a layer to the ability, that makes it's safe use not guaranteed under normal circumstances.