I think Nightmare is the best card in Splinterlands on Gold level and above. It has an amazing speed and phaze. If you include some slow or swiftness it can be almost impossible to hit and is a great counter for both Yodin and magic teams. In this battle we even take down Llama Kron on 17 mana:
https://splinterlands.com?p=battle&id=sl_acebaafb47258ff0d5a864e35af5d143&ref=truls
This is a very cheap team except of Undead Priest, that can be substituted by ooze
Combined with Kitty it is a monster that can take down almost any team
https://splinterlands.com?p=battle&id=sl_6deec538d2b7bddfad9f60aae4e904b6&ref=truls
But you can have the same effect with Thaddius Brood. You will be very happy when you see Grum on the opposite side
https://splinterlands.com?p=battle&id=sl_f804da66176189bcd25742b5b9ea4c44&ref=truls