Guardian of New Benalia — ruling 1

Guardian of New Benalia's second ability triggers whenever its controller taps another creature for Guardian of New Benalia's enlist ability.

Guardian of New Benalia — ruling 2

You may activate Guardian of New Benalia's last ability even if it's already tapped. You may also activate that ability multiple times in the same turn, even if Guardian of New Benalia already has indestructible.

Guardian of New Benalia — ruling 3

The attacking player chooses whether to tap a creature for an enlist ability immediately after they tap the creatures that they have chosen to attack with. You can't choose to enlist a creature later.

Guardian of New Benalia — ruling 4

To enlist a creature, that creature must be untapped, it must not be attacking (even if it has vigilance), and it must have haste or have been under that attacking player's control since the beginning of their current turn.

Guardian of New Benalia — ruling 5

When a player taps a creature for an attacking creature's enlist ability, that attacking creature gets +X/+0 until end of turn, where X is the tapped creature's power. This is a triggered ability that goes on the stack immediately after attackers have been declared in the declare attackers step.

Guardian of New Benalia — ruling 6

You may tap only one creature for an enlist ability of an attacking creature, and a single creature can't be tapped for more than one enlist ability.

Guardian of New Benalia : règles, fonctionnement et interactions (MTG)

Guardian of New Benalia 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

Enlist (As this creature attacks, you may tap a nonattacking creature you control without summoning sickness. When you do, add its power to this creature's until end of turn.) Whenever this creature enlists a creature, scry 2. Discard a card: This creature gains indestructible until end of turn. Tap it.

How it works : Guardian of New Benalia

Original English text — Wizards of the Coast / Scryfall

#1September 9, 2022· Wizards of the Coast
Guardian of New Benalia's second ability triggers whenever its controller taps another creature for Guardian of New Benalia's enlist ability.
No other card is named in this ruling.
#2September 9, 2022· Wizards of the Coast
You may activate Guardian of New Benalia's last ability even if it's already tapped. You may also activate that ability multiple times in the same turn, even if Guardian of New Benalia already has indestructible.
No other card is named in this ruling.
#3September 9, 2022· Wizards of the Coast
The attacking player chooses whether to tap a creature for an enlist ability immediately after they tap the creatures that they have chosen to attack with. You can't choose to enlist a creature later.
No other card is named in this ruling.
#4September 9, 2022· Wizards of the Coast
To enlist a creature, that creature must be untapped, it must not be attacking (even if it has vigilance), and it must have haste or have been under that attacking player's control since the beginning of their current turn.
No other card is named in this ruling.
#5September 9, 2022· Wizards of the Coast
When a player taps a creature for an attacking creature's enlist ability, that attacking creature gets +X/+0 until end of turn, where X is the tapped creature's power. This is a triggered ability that goes on the stack immediately after attackers have been declared in the declare attackers step.
No other card is named in this ruling.
#6September 9, 2022· Wizards of the Coast
You may tap only one creature for an enlist ability of an attacking creature, and a single creature can't be tapped for more than one enlist ability.
No other card is named in this ruling.