Three Main Reasons That ability that Karakas has to return a legendary creature to its owner's hand is actually a three-fold effect, one that gets even more powerful, and even more oppressive, in Commander, where oftentimes your deck can be designed around your commander
This is generally worse than a Merfolk Lookter in these kinds of decks as you are only able to get the discard in your combat step making it quite unsuitable for some of the cheat in effects
The mechanic may pop up in a Horizons set as a callback, but I dont expect to see it outside of an edge case like that
WWW - Hydro Pump (40+) Effect: Does 40 damage plus 10 more damage for W Energy attached to Blastoise but not used to pay for this attack's Energy cost
You can thank Aaron for the card Hide on the Ceiling, which he really wanted to get on a card
The other part is that creatures your opponents control attack if able