im not sure about this card... you usually mulligan for early game (doomsayer/ravens/tarcreepers/ etc) to survive till round 5-6-7 where you can clear board with aoe... So why would you want to duplicate early game stuff on round 9+... It's also so slow to drop 8 mana cost minion without immediate effect vs most opponents... So far it looks BAD
It is like the warrior omega spell, usually the mechs are not that great but is 3 for 1 card and don't make you closer to fatigue.
If this card put extras doomsayer, tarcreeper, raven and one Meteor comes to your hand in mulligan is enough value for the cost.
It is slow, terrible tempo, but decent value in a control deck, unfortunately non warlock control decks are dead.
I really like this card because you can also start planning early, which adds skill to the game. Suppose you get 3 early game cards in your mulligan. Do you shuffle 1 back to get a bigger card for more value with this card? Or exactly the other way around, 3 late game cards: do you keep 1? And in what matchups do you make this decision? Expect fatigue because it is a priest or warrior opponent, mulligan arcane intellect then?
This would help out aggro mage for getting Prince Keleseth back into their hand and possibly Zola as well, This could work for control for getting more blizzards and removal tools. Getting Hex Lord Malacrass in your hand could give you infinite value and never fatigue by shuffling cards into your deck but I'm not sure its battlecry would prevent him from being put back into your hand again.
There aren't enough words to express how wrong you are in all of your points (read the card text again then)