Use a counter to represent [creature]." Obviously "counters" and "tokens" became very different things, although that wording does harken back to how I suggested using dice as tokens in my above-mentioned teachings session
If you want to go even further, you can try building creatureless Foxglove
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
The first section, above the type line, contains their chapter abilities, and the second section, below the type line, contains any other abilities (or italicized flavor text)
For more info on those, click those links
#5 - Snapcaster Mage Wizards find themselves on the Magic Invitational Cards often, Snapcaster Mage being the most recent of them