The only caveat is you must sacrifice a creature in play in order to search, and the creature you look for must have a converted mana cost of exactly one more than the sacrificed creature
While not too powerful on its own, Toph's primary strength comes from letting you still get the benefits of your full mana pool by temporarily Earthbending artifacts instead, while doubling the mana potential of cards like Chromatic Lantern if activated in the correct order
If you choose the second mode and your creature is not a legal target as Archdruid's Charm resolves, you won't put a +1/+1 counter on it, and no damage will be dealt
Even the -1 can be scary in a Populate deck, like Ghired, Conclave ExileGhired, Conclave Exile, or a deck that can duplicate the trigger, such as Adrix and Nev, TwincastersAdrix and Nev, Twincasters