In the Trenches — ruling 1

The activated ability is a single ability that creates two one-shot effects: one that exiles the permanent when the ability resolves, and another that returns the exiled card to the battlefield immediately after In the Trenches leaves the battlefield.

In the Trenches — ruling 2

If In the Trenches leaves the battlefield before its activated ability resolves, the target permanent won't be exiled.

In the Trenches — ruling 3

Auras attached to the exiled permanent will be put into their owners' graveyards. Equipment attached to an exiled creature will become unattached and remain on the battlefield. Any counters on the exiled permanent will cease to exist.

In the Trenches — ruling 4

If a token is exiled, it ceases to exist. It won't be returned to the battlefield.

In the Trenches — ruling 5

In a multiplayer game, if the owner of In the Trenches leaves the game, the exiled card will return to the battlefield. Because the one-shot effect that returns the card isn't an ability that goes on the stack, it won't cease to exist along with the leaving player's spells and abilities on the stack.

In the Trenches — ruling 6

The activated ability can only be activated once per game. If the ability is countered or otherwise fails to resolve after being activated, it can't be activated again.

In the Trenches — ruling 7

If In the Trenches leaves the battlefield and later returns to the battlefield, it is a new object on the battlefield with no memory of the last time it was there. Its ability may be activated, even if it was activated a previous time it was on the battlefield.

In the Trenches : règles, fonctionnement et interactions (MTG)

In the Trenches 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

Creatures you control get +1/+1. : Exile target nonland permanent you don't control until this enchantment leaves the battlefield. Activate only as a sorcery and only once.

How it works : In the Trenches

Original English text — Wizards of the Coast / Scryfall

#1October 14, 2022· Wizards of the Coast
The activated ability is a single ability that creates two one-shot effects: one that exiles the permanent when the ability resolves, and another that returns the exiled card to the battlefield immediately after In the Trenches leaves the battlefield.
No other card is named in this ruling.
#2October 14, 2022· Wizards of the Coast
If In the Trenches leaves the battlefield before its activated ability resolves, the target permanent won't be exiled.
No other card is named in this ruling.
#3October 14, 2022· Wizards of the Coast
Auras attached to the exiled permanent will be put into their owners' graveyards. Equipment attached to an exiled creature will become unattached and remain on the battlefield. Any counters on the exiled permanent will cease to exist.
No other card is named in this ruling.
#4October 14, 2022· Wizards of the Coast
If a token is exiled, it ceases to exist. It won't be returned to the battlefield.
No other card is named in this ruling.
#5October 14, 2022· Wizards of the Coast
In a multiplayer game, if the owner of In the Trenches leaves the game, the exiled card will return to the battlefield. Because the one-shot effect that returns the card isn't an ability that goes on the stack, it won't cease to exist along with the leaving player's spells and abilities on the stack.
No other card is named in this ruling.
#6October 14, 2022· Wizards of the Coast
The activated ability can only be activated once per game. If the ability is countered or otherwise fails to resolve after being activated, it can't be activated again.
No other card is named in this ruling.
#7October 14, 2022· Wizards of the Coast
If In the Trenches leaves the battlefield and later returns to the battlefield, it is a new object on the battlefield with no memory of the last time it was there. Its ability may be activated, even if it was activated a previous time it was on the battlefield.
No other card is named in this ruling.