These effects are so much better when they give you a way to clear lands off your library, and this case gives you up to two land drops off the top each turn
Not only does Mavinda give us another way to trigger heroic, but her effect will allow you to put the spell back into your hand
It is one of the most easily cheated into play cards along with the Sphinx as it is an artifact and a creature while still having colour and can reside in a graveyard
For that reason, Id include a fair amount of artifact mana cards that cost three mana, like Darksteel Ingot
And, of course, he was using other cards to also get good use out of the Norin the Wary shenanigans: Now, all of these concepts are pretty typical for the Norin the Wary builds of Soul Sisters
This card also has a nice activated ability for myr typal decks, but I think it still works well even if you dont plan to use its second ability