I can see this being a nice bit of politicking in spirits, and you wont hate it in your opening hand
Sacrifice outlets and repeatable egg-makers turn Atla into a reliable engine that overwhelms opponents with must-answer creatures
1 Hidden Hideout 1 Cinder Glade 1 City of Brass 1 Dragonskull Summit 1 Exotic Orchard 1 Fabled Passage 1 Grand Coliseum 1 Hinterland Harbor 1 Rain-Slicked Copse 1 Rootbound Crag 1 Smoldering Marsh 1 Sodden Verdure 1 Spire Garden 1 Sunken Hollow 1 Undergrowth Stadium 1 Vernal Fen 1 Escape Tunnel 1 Turtle Lair 1 Ash Barrens 1 Command Tower 1 Evolving Wilds 1 Path of Ancestry 1 Thriving Grove 1 Thriving Isle 1 Thriving Moor 1 Vibrant Cityscape 2 Plains 2 Island 2 Swamp 2 Mountain 4 Forest Each Turtle Power

Pay X mana and remove X +1/+1 counters from Marath, and you can do one of the following: Put X +1/+1 counters on target creature Have Marath deal X damage to target creature or player Put an X/X green elemental creature token onto the battlefield This means if you get infinite mana, you can pull all the counters off of Marath to use his ability, send him to the command zone, recast him, and do it again until your opponents are all dead or you have an infinitely wide board of infinitely large creatures
But Feline Ferocity essentially took a Tribe, Cats, without a major identity, and gave us a strong one