Reversing the effects of a spell that is successful is impossible. Spells work with natural order and if successful have an eternal marker on what they affect.
What you're looking for is to reprieve, cease, dissolve, neutralize, or counter the side effects of the spell cast. You don't target the spell, you target the resulting outcomes.
This can be done either all together or taking the effects on individually. All together they'll be harder to pinpoint and account for. Individually they'll take longer and will be harder to take accurate measure without disturbing your goal further.
Either direction you take this you should design your own spell(s). It will ensure better accuracy and efficacy. Chances are you're more likely to successfully counter the spell cast if a spell or spells are designed specifically for the spell they are countering.