Vault Skyward — ruling 1

Vault Skyward can target any creature, including one that already has flying or is already untapped.

Vault Skyward — ruling 2

For flying to work as an evasion ability, Vault Skyward must be cast before the declare blockers step begins. Once a creature has become blocked, giving it flying won’t change that.

Vault Skyward : règles, fonctionnement et interactions (MTG)

Vault Skyward 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

Target creature gains flying until end of turn. Untap it.

How it works : Vault Skyward

Original English text — Wizards of the Coast / Scryfall

#1January 1, 2011· Wizards of the Coast
Vault Skyward can target any creature, including one that already has flying or is already untapped.
No other card is named in this ruling.
#2January 1, 2011· Wizards of the Coast
For flying to work as an evasion ability, Vault Skyward must be cast before the declare blockers step begins. Once a creature has become blocked, giving it flying won’t change that.
No other card is named in this ruling.