That card is Squee, Dubious Monarch, the newest iteration of the recurring character Squee, who has always been depicted as a Goblin that comes back from the grave over and over again. Unlike his previous two iterations however, this version of Squee is actually an impactful card for the mana invested rather than just being a highly recursive three-mana threat.
The card is incredibly close to Goblin Rabblemaster with a few small differences. Squee is legendary and has haste, while Rabblemaster forces your Goblins to attack and also gets buffed when attacking.
The biggest weakness of Goblin Rabblemaster (and its other variant, Legion Warboss) is that it’s incredibly fragile to removal. However, Squee being able to escape from the graveyard and attack for four mana greatly mitigates this weakness.
Goblin Rabblemaster with escape is a pretty ridiculous card, and unlike the most popular escape card currently in Modern, Kroxa, Titan of Death’s Hunger, Squee gives you a powerful and proactive play for your mana investment rather than an underwhelming discard effect like front half of Kroxa.
I’ve really liked Kroxa so far in various red/black/x midrange shells in Modern and I’m excited to see where the card ends up going forward.