Explore lets Hakbal decks utilize a huge range of possible sub-themes with their merfolk: +1/+1 counters, landfall, self-mill and recursion, topdeck mechanics like cascade and discover, even hand-size matters and self-discard
Battle damage is applied normally
The same is also true of any other abilities that modify how a land enters the battlefield or apply "as" a land enters the battlefield, such as the first ability of Cavern of Souls
Final Fortune + Last Chance + Warriors Oath Two mana for an extra turn is an insane rate
In practical application, this means that, while each deck is unique, there is one basic set of cards that comprise all of the unique decks, so you will see the same creatures, artifacts, etc
Its a versatile sweeper that sees most play these days in Commander