Here's scenario:

The rebel player is attacking and rolls 1 damage and a surge which they decide to spend on Pierce. The Imperial player rolls 3 blocks. The blocks negate the 1 damage but does pierce still do damage or do the excess 2 blocks soak up the damage?

Also do surges only take affect if an attack lands? So if a surge is spent on Stun does the attack actually have to do damage for Stun to take effect?

Thank you.

It's sorta the other way around in regards to "Pierce": a "Pierce 1" will ignore 1 "Block" result. So in your example the defender in reality only rolls 2 Blocks. This is still enough to negate the single "Damage" rolled so the defender isn't hit and doesn't suffer any damage.

And suffering damage is a necessity in order for other keywords like "Stun" or "Blast" to take effect. I don't know if you're familiar with X-Wing but there are many parallels in how hit and damage effects happens.

Check out "Conditions " on page 9 in the Rules Ref.

Hope that helps. Cheers