Combat

[TreeTopSky]

I choose my attackers, opponent chooses his blockers, I play {Dramatic Rescue} to return his blocker to his hand. Does my opponent still take the damage?

[Giggle the Draco Genius]

Once a creature has been blocked it remains blocked and as such it will not do damage to the defender.

509.1h An attacking creature with one or more creatures declared as blockers for it becomes a blocked creature; one with no creatures declared as blockers for it becomes an unblocked creature. This remains unchanged until the creature is removed from combat, an effect says that it becomes blocked or unblocked, or the combat phase ends, whichever comes first. A creature remains blocked even if all the creatures blocking it are removed from combat.

The exception to the rule is a creature with trample, trample will then apply the full damage to the defender.

702.19c If an attacking creature with trample is blocked, but there are no creatures blocking it when damage is assigned, all its damage is assigned to the player or planeswalker it's attacking.

[Double-O-Scotch]

No. Once a creature is declared as blocked, it's blocked regardless of what happens to the blocker. The only exception is creatures with trample. A creature with trample (we'll say 3/3) is blocked by a 5/5. And The blocker is removed before combat damage for some reason (bounced, exiled, destroyed)  3 damage would get through

[TreeTopSky]

But the combat didnt go through. I chose to attack with said creature, and he was choosing his blockers. I played an instant before the damage was dealt to return said blocker to his hand.

[Double-O-Scotch]

Did your attacker have trample?

[Giggle the Draco Genius]

So the combat phase is broken down into five steps.

Begin Combat
Declare Attackers -> you chose your attacker here
Declare Blockers -> opponent chose blocker here, you cast {dramatic rescue} here
Damage Step -> The creature you attacked with is still considered blocked as the opponent already chose the blocker and does no damage.
End Combat

[TreeTopSky]

Thanks for breaking that down, Giggle. I understand.

[MuggyWuggy]

Resolved