Federation is an ability word introduced in Star Trek. Federation abilities count the number of different creature types among non-Borg creatures you control, rewarding a diverse crew over a single typal army. Creature types on Borg creatures don't count, even if that creature has other types.
Sarek, Federation Ambassador draws a card for every five creature types at the beginning of combat, while Starfleet Academy turns a diverse board into a burst of mana. Infinite Diversity copies an instant or sorcery from your graveyard once for each type, so creatures with several types, or every type, push the count up fast.
