On the front, Cosima is a little hard to parse, but essentially, she works like so: at the beginning of your upkeep, you exile Cosima
You can play this black ramp piece in other color combinations thanks to Urborg, Tomb of Yawgmoth, but those decks make this black land a weak half of a 2-card combo
Standard, for example, is a rotating format, meaning it only allows you to play specific cards that have been printed in recent times
Now, if you want to do something incredibly innovative with your custom card, like introducing a custom frame or weaving together text and image like some Secret Lairs do, Photoshop/Gimp is likely the way to go
Any good EtB or attack-trigger printed in the future can potentially do some crazy stuff with a Rionya involved