The exceptions are when a card has a golden border, as seen on Magic Golden Flower, and on action cards, like One Jump Ahead, where the card text takes effect immediately
Firstly, be on the lookout for cards that make players lose 4 or more life when combined with Ystholas first trigger, like Will of the Abzan and Rush of Dread
Play or Draw in Limited Frankly, a topic most players dont even spare a thought about anymore, where I think I am having a different take than most: More often than not, it makes total sense to get yourself that extra card that you deserve
for Cats I found having too many cats wasn't very useful, I went a bit extreme, down to 14 cats, but 28 is a lot
* If youre looking for other great Dueling Wizards card games, I personally recommend Ashes: Rise of the Pheonixborn
That said, ability doubling is strong, regardless of what strategy you're aiming for, and many old ally cards have ETBs worth doubling with Katara in play