Koth might not be able to defend himself, but if you can cast a burn spell in that same turn, taking out the attacker, maybe thats enough
This sets a huge red target on your legendary vampires backs, so make sure to play ample creatures to prevent having to put all your eggs into one basket
Alternatively, you could play Sheriff of Nottingham, Corrupt Official with Simba, Fighting Prince - whose ability, Step Down or Fight, gives players the option to draw two cards and discard two cards whenever they banish another character in a challenge, or The Queen, Disguised Peddler, which allows you to tap it to discard a character to gain lore equal to the amount of lore that character can gain
A non-combo Vivi deck
Limited print promo cards, like Survival of the Fittest and Gandalf the White, can fetch high prices
While the white ability, to gain five life for three mana, is the only irrelevant ability, and the rest are situationally good