They reduce the strength of a character by one for each Micrbot you have in play
For example, if Strata Scythe's imprint ability ("When this Equipment enters, search your library for a land card, exile it, then shuffle.") triggers twice (probably because it somehow entered attached to Cloud), up to two total land cards can be exiled
Hatsune Miku: Sakura Superstar Elvish Mystic Elvish Mystic has always been one of greens best ramp creatures, and here it shows up as a bonus card in the Sakura Superstar Secret Lair
Moogles (from Final Fantasy 6): Depicting their heroic moment rescuing Tina, with effects mirroring their in-game ability to become powerful reinforcements
Hopefully these options give you ideas on how to best handle your storage needs
But for FF, these four decks end up feeling strangely insufficient