At the beginning of combat on your turn, each Merfolk creature you control explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on the exploring creature, then put the card back or put it into your graveyard.)
Whenever Hakbal attacks, you may put a land card from your hand onto the battlefield. If you don't, draw a card.
Flood the board with Merfolk, then use Hakbal's combat-step explore trigger to grow your team and dig for lands and gas every turn. You snowball card advantage and counters while ramping aggressively, eventually swinging wide with a buffed, evasive Merfolk army backed by tribal lords and a finisher.
Massive repeatable card advantage and selection via explore every combat
Built-in ramp from both explore (lands to hand) and the attack trigger (lands to battlefield)
Cheap commander (4 MV) that snowballs the whole board, not just itself
Deep, supported Merfolk tribal pool with lords and evasion
Explore triggers are wasted if Hakbal is removed, so it's heavily commander-dependent
Goes wide, making it vulnerable to board wipes and sweepers
Can lack reach/interaction in a typical GU shell
Slow to close if the early Merfolk curve doesn't materialize
Cheap lords/anthems that turn explored Merfolk into a lethal wide attack.
Tighten the curve with cheap, efficient Merfolk and stack multiple lords plus evasion enablers (islandwalk) so your explored board is hard to block. Add counter doublers (Branching Evolution, Doubling Season) and proliferate effects to maximize explore value, and include protection like Heroic Intervention and a Lightning Greaves/Swiftfoot Boots to keep Hakbal online. Top-end finishers such as Craterhoof Behemoth or Triumph of the Hordes convert your wide board into reliable lethal damage.
Legendary Creature — Merfolk Scout
