You pay all costs and follow all normal timing rules for cards played this way
Of all the Final Fantasy Summon spoilers we saw in todays debut panel, Bahamut is undoubtedly the most exciting
Two mana outlay with essentially a free card thereafter is really good
While Elderfang Disciple and Acquisitions Expert are basically the same card, if we have both in our opening hand, it's best to play Elderfang Disciple first since it's a Cleric, which will allow allow us to see two cards with Acquisitions Expert's enters-the-battlefield trigger the next turn
Then you can toss double those counters here as +1/+1 ones
But the real treasure is its ETB ability that lets you swipe an instant or sorcery from an opponents graveyard, exile it, and cast it that turn using any mana, making it beneficial for attrition or grindy matches