Lets take a look at each levels power: Level One In a flavor win, you want your Ring-bearer to be small with low power in order to sneak past blockers, which has Halflings written all over it
Raksha Golden Cub [Cat]: In late-game commander, this will boost your army by a lot
Flanking means "Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn." If a creature gains flanking during combat, that has no effect on any creature already blocking it
Getting extra main phases during your turn with effects like Relentless Assault or Seize the Day, for example won't make survival trigger again
You can, for instance, transform Mimeoplasm into Invisible Stalker to make it unblockable, attack, then transform it into Terisian Mindbreaker to give it some extra, half-the-deck-milling oomph as it slams into your opponent, then transform it into Seedborn Muse to untap it, then transform it into Ulamogs Dreadsire to pop out a 10/10 for giggles