First Response — ruling 1

Damage dealt to you causes you to lose that much life.

First Response — ruling 2

First Response looks at the entire previous turn to determine whether its ability triggers or not. It doesn't matter whether First Response was on the battlefield when you lost life.

First Response — ruling 3

First Response checks only if you lost life during the turn, not whether your life total decreased over the course of the turn. For example, if you lost 2 life and then gained 8 life last turn, First Response's ability will trigger.

First Response — ruling 4

Only one Soldier will be created no matter how much life was lost.

First Response — ruling 5

The Soldier won't be able to attack the turn it's created (unless something gives it haste).

First Response : règles, fonctionnement et interactions (MTG)

First Response 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

At the beginning of each upkeep, if you lost life last turn, create a 1/1 white Soldier creature token.

How it works : First Response

Original English text — Wizards of the Coast / Scryfall

#1November 10, 2020· Wizards of the Coast
Damage dealt to you causes you to lose that much life.
No other card is named in this ruling.
#2November 10, 2020· Wizards of the Coast
First Response looks at the entire previous turn to determine whether its ability triggers or not. It doesn't matter whether First Response was on the battlefield when you lost life.
No other card is named in this ruling.
#3November 10, 2020· Wizards of the Coast
First Response checks only if you lost life during the turn, not whether your life total decreased over the course of the turn. For example, if you lost 2 life and then gained 8 life last turn, First Response's ability will trigger.
No other card is named in this ruling.
#4November 10, 2020· Wizards of the Coast
Only one Soldier will be created no matter how much life was lost.
Card named in this ruling
Soldier
#5November 10, 2020· Wizards of the Coast
The Soldier won't be able to attack the turn it's created (unless something gives it haste).
Card named in this ruling
Soldier