Mortality Spear — ruling 1

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Mortality Spear). Mortality Spear's mana value is always 4, no matter what the total cost to cast it was.

Mortality Spear : règles, fonctionnement et interactions (MTG)

Mortality Spear 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

This spell costs less to cast if you gained life this turn. Destroy target nonland permanent.

How it works : Mortality Spear

Original English text — Wizards of the Coast / Scryfall

#1April 16, 2021· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Mortality Spear). Mortality Spear's mana value is always 4, no matter what the total cost to cast it was.
No other card is named in this ruling.