Merciless Javelineer — ruling 1

Once a creature has blocked, Merciless Javelineer’s ability can’t undo that block.

Merciless Javelineer — ruling 2

The target creature won’t be able to block even if the -1/-1 counter is removed from it or if the -1/-1 counter can’t be put on it.

Merciless Javelineer : règles, fonctionnement et interactions (MTG)

Merciless Javelineer is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

, Discard a card: Put a -1/-1 counter on target creature. That creature can't block this turn.

How it works : Merciless Javelineer

Original English text — Wizards of the Coast / Scryfall

#1April 18, 2017· Wizards of the Coast
Once a creature has blocked, Merciless Javelineer’s ability can’t undo that block.
No other card is named in this ruling.
#2April 18, 2017· Wizards of the Coast
The target creature won’t be able to block even if the -1/-1 counter is removed from it or if the -1/-1 counter can’t be put on it.
No other card is named in this ruling.