Each time this card declares an attack, you must Tribute 1 Aqua-Type monster.
In case you were wondering: Use Mythic Depths, and summon this. Wait 1 turn. Activate Stray Lambs, Shooting Star Bow Ceal, Secret Pass to the Treasures, then Storm. OTK. That's a highly unlikely scenario but I'm just saying it's technically possible.
Ok I understand that op was also using a really bad example way to much set up for something mediocre honestly this hydra isn't that good in general people trying to build around it are ........noobs
Lmao Duel Links' 3 monster-space limit makes it literally inpossible for this card to actually use its effect to the fullest and attack 3 times in a turn, unless you start reviving monsters during your battle phase with Soul Ressurection or something...