Mindspring Merfolk has a great Exhaust card draw ability (pay ,: Draw X cards) that is combined with a mass Merfolk Tribal buff: a +1/+1 counter on each Merfolk creature we control. That ability is limited (as it can be activated only once), yet powerful for such a low mana drop, making it a great option for our build with both Tribal and +1/+1 counters synergy.
Bred for the Hunt is by no means a worse option for card draw, but gets cut because it is more generic, while Mindspring Merfolk seems to score a bit higher in synergy due to combination of Tribal and +1/+1 counters synergy.
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