In theory, with a Naban, Dean of Iteration on the battlefield, you only need half the number of blue mana symbols on the battlefield to make Master of Waves good (for example, in the worst-case scenario where you have just a Naban, Dean of Iteration and a Master of Waves, you'll still end up with 10 power across five bodies, which is a pretty reasonable deal for four mana, and if you throw just one other Wizard into the mix, things cat get out of hand really quickly when Master of Waves' enters-the-battlefield trigger is doubled)
Youre happy with the land count, the removal and everything else
Bounce, draw, or tap
If Mystic Confluence is copied, the effect that creates the copy will usually allow you to choose new targets, but you can't choose new modes
If you dont cast the card, perhaps because you choose not to or because its a land card, it remains exiled
This is quite excellent, as whenever its controller attacks, they create a tapped and attacking 1/1 Human token for each opponent