Cost: 2.

Hero Interrupt: When your hero's attack deals any amount of excess damage, increase that amount by 1.

"That's a little excessive..."
Galaxy's Most Wanted #45.
Follow Through

An archetype-specific card, but a solid synergy piece/build-around in that archetype. Are you running a critical mass of Into the Fray, Relentless Assault, Moment of Triumph, and Hand Cannon? Possibly on a hero with built-in cards with overkill (Rocket's Particle Cannon, Thor's Hammer Throw), or which already synergize with some of those (Ms. Marvel's Embiggen)? Include Follow Through and go to town.

Example Thor deck:

I'm a believer! I originally overlooked this card, then tried it in my Thor deck just for fun... Man is it good! — neothechosen · 9705
It was great playing it with Wasp as well. — DoxaLogos · 206

I'm also intrigued in knowing how this will work with Wasp's Giant ability... Let's assume I have 2 Follow Through in play, and I have two engaged minions with 1 HP remaining each. If I attack them, using Hand Cannon's boost and deal 2 and 2 damage... this means that the villain will be dealt 6 damage, or I'll be able to trigger each Follow Through just once? (because it's just one attack)

wehehe · 129
I believe it is 6 damage to the villain as its similar to the ruling on Melee and Ms Marvel's Embiggen!. Together it combos for 5 damage and 5 damage on 2 different enemies. — MillerTime · 1