You don't need Tirion, but you do need Mysterious challenger for an aggro type of secret santa to reach high rank the easy way. Midrange paladin works too but its not nearly as good mainly the bot has no clue how to use cards like Ironbeak owl/Keeper of uldaman/aldor peacekeeper/ any discovery cards properly which leads to free win for the opponents.
Atm the cards to avoid in deck making is while using Silver for pala is(for me at least): Sir Finley, discovery cards, silence cards. Even though I still stick an Ironbeak owl in most decks for experiements.
Other cards which doesnt work very well for other classes includes Void Terror, Reno Jackson, Battle rage incl. most warrior combo cards.
Edit: sticking to paladin theme recommendations.