If it's getting an early bgh without any 7 drops out then that's bad but an early shredder is good isn't it? To avoid wasting it just create any combo that included innervate and set the penalty for using innervate outside of the combo (the number after the card ID) to something like 25. If you put in every potential combo you want then you could raise the penalty more but if you're not sure of all the possibilities then keep the penalty low so that it has the chance to still use it when it will give good board value.

Combo's have a different format than mulligans. See this: http://www.hearthranger....h-update.aspx#post27750

Take this one for example: NEW1_022,200;CS2_106,10;bonus:500

It says "NEW1_022 has a 200 penalty for being played outside a combo, CS2_106 has a 10 penalty for being played outside a combo, and together they have an extra 500 bonus." Penalties and bonuses are just board value numbers which is explained a bit at the end of the linked post. The penalty keeps cards from being played outside combos because it is reducing the board value that the card gives on its own, but if the penalty is low then it has a chance to be played outside the combo when it gives good board value. The bonus just makes it so that when you have a combo, the combo gets played over other options because you are giving extra board value to the combo. Silverfish just plays whatever it thinks gives the best board value for the turn.

It can be really tricky nailing down the right penalties and bonuses. If it's a "soft" combo that gives a little extra value but isn't absolutely required like playing southsea deckhand when you have a weapon then you want to keep the penalty and bonus low but if it's more of a "hard" combo that you almost always want to be played together like force of nature+savage roar then you need to raise them up. Sometimes you'll want no bonus and sometimes you'll want no penalty.