Strike goliaths deploy in teams of two from Nova's factory for a cost of 750 minerals and 250 gas. Compared to normal goliaths they have greatly increased HP and damage. Each goliath has an individual name and has the rank of captain.
They are not very efficient at dealing damage, especially compared to Swann's goliaths with their Multi-Lock upgrade, but to make up for it Nova's strike goliaths can stun enemy carriers and battlecruisers, making them very useful against certain hard compositions. If not fighting those air units and there is some spare gas left over, it would likely be more useful to spend it on covert banshees instead, which have better anti-ground DPS.