As for tactics, I don't know... I honestly don't know. Devil's Strike + Curse Mark in a duel has saved me many times from golems and vampire griffons. The main thing in attack is to upgrade magic speed.
If I set the defense to 5, it doesn't mean it's the last one in the upgrade... it might not even appear at all, although the percentage is quite high, or it might be there from the very beginning (Marbas).
Добро и зло,
Есть сила и власть,
И много всего
Но знай ты одно,
Что все это чушь,
И лишь без любви
Не проживешь ты и дня..