Long time ago when Meditation amulet was a promo i voiced my concern. (
http://forum.arcanewonders.com/index.php?topic=12950.0)
Most people called it trash just by looking at it. "it takes 2 actions, and then your still down 1 mana."
However after some time meditation amulet anyway found its way into the meta. It was definitely not used by all (spawnpoint) books, but it was represented occasionally and with mixed success. Back then necromancers seemed to benefit the most from it and could often get away with spending their full action on building their manapool while libro pumped out brutes.
After some time it saw more and more play and was eventually perceived as a good card with its uses.
(Rather recently) a few other cards has been released which also exchanges actions to mana.
Remove curse
Disperse
Crumble
Besides this we got new mana generators:
Wispwillow Amulet
Mana Lotus
Remove curse (can be used to generate mana only and not removing.)
Ritual of Kallek
Ritual of Kallek is a chapter of its own. Since this card is in the game it more or less nullifies the other generators, but im still mentioning them because even without Kallek they still try to do what Kalleks does but in a less efficient and/or consistent way which could potentially still be a problem even if Kallek was errataed or banned.
Before i move on:
Looking at any single card isolated is not very interesting. Its how a card synergies with other cards and mechanics of the game.
So whats is the problem?
In short: Rush / fast books cannot compete anymore.... AT ALL. They are dead with the current card pool.
It has for a LONG time (many releases) been an uphill battle to rush vs defensive spawnpoint mages who stays in their starting zone. But the combination of the above mentioned cards simply wrecks the last tiny chance fast books had vs them.
Its pretty simple... the time (rounds) it takes for you to cross the board and either engage the opponent mage or attempt to get board control is longer than the time that it takes for your opponent to recover his initial mana expense of the spawnpoint(s).
Im not gonna go in to the details on how this is performed by the defensive player... if you disagree with this feel free to try any fast book of yours and attempt to beat my tripple spawnpoint necromancer, my gate wizard....and for the sake of it... i could make a Priestess abusing the above mentioned cards as well. (This is on OCTGN.)
Kallek is potentially the biggest but not the only problem. Crumble and Disperse also deserves to be mentioned.
It used to be the case that (not counting discount rings) that casting an enchantment and benefiting from it before it would be dispelled would leave you ahead in the sense that for instance with a bear strength you would have gotten 1 attack off with more dice leaving the offensive player in some sort of an advantage after he nullified your quick cast.
Crumble and Disperse skews this in a problematic way... It makes undoing too easy and adds to the forgiveness of the initial mana sink of the spawnpoints.
All in all there are too many ways to get mana back too fast.
Without having played a single domination game at this point, i'm leaning more and more to that format being the best for MW since it wont allow you to sit in your corner and just abuse you start 5 zones from each other and correspond correctly to your opponents actions.