"When this kills a blocking unit, the blocker doesn't deal damage back."
Units which possess Quickdraw are indicated by a gun (a pistol?) in the icon slot.
What Does Quickdraw Do?
As the name suggests, a unit with Quickdraw shoots first when attacking. In game terms this means that if a Quickdraw unit is blocked but has enough damage to kill the blocker, it takes no damage itself.
Note that this only works if the Quickdraw unit actually kills the blocker. If it merely damages it then the blocker is able to fight back, possibly killing the Quickdraw unit
The tooltip for the skill is very precisely worded: "When this kills a blocking unit, the blocker doesn't deal damage back." In other words, Quickdraw only works when attacking, not when you're the one defending as a blocker.
Last updated: 20-02-2017
This page written for Eternal version 1.16, Card Set 1