Yep, if you know the enemy has the Talisman you may as well give up on ECM or any other 'chance to hit' modifiers. Bulk up on armor and/or shields and make sure you have the best combat sensors for yourself. Or use seekers that don't need to calculate chances to hit!
Luring him into a minefield is also a good option. Bring a minelayer or two with your fleet, stop where you expect to be attacked and lay mines, then let him come to you!