Herald of Secret Streams
Creature — Merfolk Warrior
Creatures you control with +1/+1 counters on them can't be blocked.
"You might as well try to stop the waterfall."
Sara Winters
The List (PLST)
• #XLN-59Rulings
Once a creature you control has become blocked, putting a +1/+1 counter on it won't cause it to become unblocked.
(wotc • 2017-09-29)
Rulings
Once a creature you control has become blocked, putting a +1/+1 counter on it won't cause it to become unblocked.
(wotc • 2017-09-29)