Bannerhide Krushok — ruling 1

If you activate Bannerhide Krushok's reinforce ability during your main phase, your opponents will have the chance to respond to that ability before you can activate the scavenge ability, perhaps by removing Bannerhide Krushok from your graveyard. However, if Bannerhide Krushok ends up in your graveyard during your main phase in such a way that there are no spells or abilities on the stack, you'll have priority to activate the scavenge ability before anyone can remove Bannerhide Krushok from your graveyard.

Bannerhide Krushok — ruling 2

Exiling the creature card with scavenge is part of the cost of activating the scavenge ability. Once the ability is activated and the cost is paid, it's too late to stop the ability from being activated by trying to remove the creature card from the graveyard.

Bannerhide Krushok : règles, fonctionnement et interactions (MTG)

Bannerhide Krushok 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

Trample Reinforce 2— (, Discard this card: Put two +1/+1 counters on target creature.) Scavenge (, Exile this card from your graveyard: Put a number of +1/+1 counters equal to this card's power on target creature. Scavenge only as a sorcery.)

How it works : Bannerhide Krushok

Original English text — Wizards of the Coast / Scryfall

#1June 18, 2021· Wizards of the Coast
If you activate Bannerhide Krushok's reinforce ability during your main phase, your opponents will have the chance to respond to that ability before you can activate the scavenge ability, perhaps by removing Bannerhide Krushok from your graveyard. However, if Bannerhide Krushok ends up in your graveyard during your main phase in such a way that there are no spells or abilities on the stack, you'll have priority to activate the scavenge ability before anyone can remove Bannerhide Krushok from your graveyard.
No other card is named in this ruling.
#2June 18, 2021· Wizards of the Coast
Exiling the creature card with scavenge is part of the cost of activating the scavenge ability. Once the ability is activated and the cost is paid, it's too late to stop the ability from being activated by trying to remove the creature card from the graveyard.
No other card is named in this ruling.