Kassai

If you activate a sword attack, and then you draw a card, you are not retroactively refunded the to activate the previous sword attack.

The cost to activate Kassai is banishing a total of four cards from your graveyard: two red cards and two yellow cards. You cannot activate Kassai if you cannot pay the cost.

You choose the cards to banish from your graveyard at the time you activate the ability. There is no priority between choosing the cards to banish and banishing them (i.e. you cannot play cards or activate abilities if you don’t have priority)

The effect does not trigger if you hit anything other than a hero (i.e. an ally). If you hit anything other than a hero first, then you hit a hero second, it will trigger.