Muxus, Goblin Grandee

When Muxus enters, reveal the top six cards of your library. Put all Goblin creature cards with mana value 5 or less from among them onto the battlefield and the rest on the bottom of your library in a random order.
Whenever Muxus attacks, it gets +1/+1 until end of turn for each other Goblin you control.

The List

Secret Lair Drop

Jumpstart 2022

When Muxus, Goblin Grandee enters the battlefield, reveal the top six cards of your library. Put all Goblin creature cards with mana value 5 or less from among them onto the battlefield and the rest on the bottom of your library in a random order.
Whenever Muxus attacks, it gets +1/+1 until end of turn for each other Goblin you control.

Jumpstart

If a card in a player's library has {X} in its mana cost, X is considered to be 0.

The bonus Muxus gets is determined only as its last ability resolves. Once that happens, the bonus won't change later in the turn even if the number of Goblins you control changes.