Can Tactical Retreat save a unit from Cull the Weak if played before it resolves?
Player A plays Cull the Weak. Player B plays Tactical Retreat in response before units are chosen. Is the unit saved? Does this also work for Ruination?

[Reaction] (Play any time, even before spells and abilities resolve.)
Choose a friendly unit. The next time it would die this turn, heal it, exhaust it, and recall it instead. (Send it to base. This isn't a move.)
Artist: Kudos Productions
Card Set: Unleashed
Player A plays Cull the Weak. Player B plays Tactical Retreat in response before units are chosen. Is the unit saved? Does this also work for Ruination?
I use Death Grip to try to kill a unit and give its Might to another unit. That unit has Tactical Retreat, which replaces its death by recalling it to base instead. Does Death Grip still give the Might bonus, since I tried to kill the unit even though it didn't actually die?
I use Bellows Breath and Tactical Retreat to retreat my Reflection token from a battlefield. Can LeBlanc still copy something at the battlefield I conquer or hold? If opponent Star-Crosses and I Tactical Retreat then Sacrifice, does the unit still go to hand?
Can I respond with Tactical Retreat and then Sacrifice on the same unit, or must Sacrifice's kill happen before I can Tactical Retreat?
I have a unit at a battlefield targeted by Hidden Blade, which will kill it and make its controller draw 2. Can I use Tactical Retreat to recall that unit to base instead of dying, and still get the draw? I was trying to use Tactical Retreat to replace the kill rather than merely dodge by leaving the battlefield.