I guess it was this?

The replay isn't quite the same. But basically he keeps casting two spells per turn, and deleting my ruler in a single turn by doing like 40 damage with each spell.
And then he can just continually AoE 4-5 of my units on the board each turn for like 15 damage each, casting Condemnation, Cosmic Ablation and Fulmination, which then leaves a status effect that does like another 10 damage at the end of their turn.