Combine that with Darkrai ex's ability that deals another 20 damage each time you attach a dark energy to the legendary monster, and you've got a deck bound to frustrate opponents
It will stick around easier than Mystic Remora and you can even buff its power to make it harder for your opponents to pay
Because the Valesk's toughness is only 2, and the Mauler has trample, which means 2 of its 4 damage gets dealt to the Valesk, and 2 gets dealt to the opponent
All of Knuckles the Echidna, Hellkite Tyrant, and Revel in Riches automatically win the game if you have a certain number of artifacts (with Revel in Riches requiring specifically Treasure tokens)
This puts more emphasis on deckbuilding, as which removal spell to use in your deck could change from week to week depending on the metagame and configuration of your deck
Strategic complexity does not need to push up the rarity of the card provided it's simple in the other two types of complexity