Hollow Marauder
Creature — Specter Rogue
This spell costs 
less to cast for each creature card in your graveyard.
Flying
When this creature enters, any number of target opponents each discard a card. For each of those opponents who didn't discard a card with mana value 4 or greater, draw a card.
Wero Gallo
Rulings
Hollow Marauder’s first ability doesn’t change its mana value, which is always 7.
(wotc • 2024-04-12)
When Hollow Marauder’s triggered ability resolves, the next target opponent in turn order (or, if it’s a target opponent’s turn, that opponent) chooses a card in hand without revealing it, then each other target opponent in turn order (if any) does the same. All chosen cards are then discarded at the same time.
(wotc • 2024-04-12)
Rulings
Hollow Marauder’s first ability doesn’t change its mana value, which is always 7.
(wotc • 2024-04-12)
When Hollow Marauder’s triggered ability resolves, the next target opponent in turn order (or, if it’s a target opponent’s turn, that opponent) chooses a card in hand without revealing it, then each other target opponent in turn order (if any) does the same. All chosen cards are then discarded at the same time.
(wotc • 2024-04-12)