The Flood of Mars — ruling 1

If the target is both a creature and a land as the triggered ability resolves, it will become a copy of The Flood of Mars. Excepting some very unusual cases, that copy won't be a land, so it won't also become an Island.

The Flood of Mars : règles, fonctionnement et interactions (MTG)

The Flood of Mars 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

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Water Always Wins — Whenever this creature attacks, put a flood counter on another target creature or land. If it's a creature, it becomes a copy of this creature. If it's a land, it becomes an Island in addition to its other types.

How it works : The Flood of Mars

Original English text — Wizards of the Coast / Scryfall

#1October 13, 2023· Wizards of the Coast
If the target is both a creature and a land as the triggered ability resolves, it will become a copy of The Flood of Mars. Excepting some very unusual cases, that copy won't be a land, so it won't also become an Island.
No other card is named in this ruling.