Kaldheim debuts the "foretell" mechanic
Are there attitudes you have to love that you have been blind to but are deeply affecting your approach to dating
For instance: if you had three Clues, enough mana, and all the relevant cards exiled under Lazav, you could cast Cackling Counterpart targeting Lazav, hold priority before it resolves, sacrifice a Clue to trigger Lazav to transform him into Marionette Master, hold priority again, sacrifice another Clue to trigger Lazav to transform into Octavia, Living Thesis, hold priority once more, cast Armor of Shadows, let everything resolve, then sacrifice a final Clue
Once you finally get to play it, it attacks with haste and buffs all your vampires permanently
Your job is to find them and mark their locations on your map
Probably need some more support in this or future sets, to make them standard playable