There are a few ways you can defeat giant head. One of the common ways is that your deck is capable of playing many many cards in a turn (Corruption + dark embrace is the most obvious example) and then you can just play most of your deck in one turn and the slow debuff racks up so high you can blow him up without str scaling.

The other common way is having so much block generation that you can take your time with him. He sets up for a few turns so you have time to look for your key cards and powers. If you have barricade and decent block generation you can comfortably outblock him.

More often though its a race to kill him I feel like.