Granting all of your Rats Toxic 1 enables a small but wide board to threaten player removal out of nowhere
The set also introduces Corrupted, an ability that becomes active when opponents have three or more poison counters
Hajar can be that Commander, and at such a cheap initial cost to play, means you have no qualms about dropping Blasphemous Act, Chain Reaction et al to clear the way for your legends to connect
This change also impacts the Expertise cycle (which will no longer be able to cheat split cards into play with their "cast for free" ability), Goblin-Dark Dwellers (which can no longer flashback a Boom // Bust), and some other less popular cards as well
It can generate mana, and if you're not using it for mana, can tap it to draw a card instead
This volume is in line with previous Mega Evolution expansions