When this creature transforms into Casal, Pathbreaker Owlbear, other legendary creatures you control get +2/+2 and gain trample until end of turn.
At the beginning of your upkeep, transform Casal.
Casal ramps you on entry by fetching a Forest, then flips into a beefy Owlbear that pumps your other legends and crashes in with trample. Build a green legends-matter beatdown shell that floods the board with cheap legendary creatures, then swing wide with the +2/+2 trample anthem on the turn she transforms.
Built-in ramp every time she enters or recasts, smoothing out mono-green's curve
Vigilance lets her attack and still block, and the Owlbear side adds trample for evasive damage
The transform anthem snowballs go-wide legendary boards into lethal alpha strikes
Cheap to cast and easy to rebuild after removal, keeping pressure relentless
Mono-green offers no interaction, leaving you exposed to control and combo decks
The anthem only triggers on transform, so timing and removal can blank your big turn
Heavily reliant on building around legendary creatures, which can be inconsistent
No card advantage engine in the command zone beyond ramp