These are typically green cards since green is the MTG color most associated with the power of nature, mana abundance, and lands
For example, if you put Spellbook (an artifact that says you have no maximum hand size) onto the battlefield and then put Doctor Octopus, Master Planner onto the battlefield, your maximum hand size will be eight
Welcome the Dead takes a little bit of work, but if you can mill yourself a bunch in a single turn (and Teval helps you get there), it can generate a ton of Zombie tokens
With how much stat-boosting goes on, it becomes very easy for Amy to hit that threshold
This can allow you to cheat in some ridiculous stuff for Bant mana, like Portal to Phyrexia in Commander, or rather unflavorfully, Doctor Octopus, Master Planner
Ledger Shredder | Illustration by Mila Pesic Birds are MTG cards that have the bird creature type