Flames of the Blood Hand — ruling 1

The damage is unpreventable, and the targeted player’s life gain that turn is replaced with nothing.

Flames of the Blood Hand — ruling 2

The replacement effect applies only to the target player, not to a permanent or player the damage might be redirected to.

Flames of the Blood Hand : règles, fonctionnement et interactions (MTG)

Flames of the Blood Hand 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

Flames of the Blood Hand deals 4 damage to target player or planeswalker. The damage can't be prevented. If that player or that planeswalker's controller would gain life this turn, that player gains no life instead.

How it works : Flames of the Blood Hand

Original English text — Wizards of the Coast / Scryfall

#1February 1, 2005· Wizards of the Coast
The damage is unpreventable, and the targeted player’s life gain that turn is replaced with nothing.
No other card is named in this ruling.
#2February 1, 2005· Wizards of the Coast
The replacement effect applies only to the target player, not to a permanent or player the damage might be redirected to.
No other card is named in this ruling.