Aside from just filling your hand with more great Knights with this trigger, it can also be used to find powerful cards like Sword of Feast and Famine and Animate Dead
Which makes perfect sense: Olivia, Opulent Outlaw's effect is based around the outlaw batching term, which includes pirates, warlocks, rogues, mercenaries, and assassins
Princess Luna could potentially be helpful if it werent for the restrictions put on pulling cards from outside the game
Otherwise, it would be pretty hard to put together a playable deck just using booster packs
It also means that all those extra Bird tokens will make your Commanders attack trigger a lot more potent on future turns
Balamb T-Rexaur is not only one of those creatures, but it also has trample and you can even trade it for a Forest in a pinch