Our stand for stats on evil enhancements says that they don’t get more than 6 total between the strength and toughness. Good enhancements are limited to a total of 7.
Sometimes for thematic purposes we will “break” that rule. For example the 10 Exodus plages all have a 1 strength but a toughness of 1-10 based on the order they took place.
Other ways we might “break” that stat limitation rule is with an X value that can exceed it. On rare occasions we have also used a negative stat on one side to balance a positive stat that exceeds the limit (like on the GE side of Leviathan).
Obviously you’re welcome to use whatever stats you feel are appropriate for the cards you create. I just wanted to share the guidelines we follow and offer some tips to how we’ve bypassed them in case you’d like to make your ideas more in tune with how the game is designed.