Why would anyone want to halve its creature attack and then let it double it for a certain cost?, I could only imagine this making sense with a growth creature, however as it would lose growth it seems pointless. And seeing that it costs 3 , One could just as well take a wyrm instead of it, providing a creature + the effect in 1 card.
Blessing, monumentum, chaos power, think about it.
Out of those, blessing is most reliable. So, say I take Dragon, and half his attack from 12 to 6.
I need
and a card slot to play this card.
Then I bless the dragon making him 9 attack creature.
Then I need to spend 2
each turn for it to have 18 dmg.
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Uses 3 cards, needs 2 different elements and has an upkeep of 2 -> dmg per turn 18
Play dragon.
Bless dragon.
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Uses 2 cards, need 1 element, has no upkeep. -> dmg per turn 15
So... another card, and another element, and an upkeep for increase of 3?
Not to mention,
already has a dive creature. It is better to buff Pegasi than wasting cards to buff Dragon.
As for other elements with buffs (gravity, entropy), they are probably also better off with just straight buffing the creature, than by using a card from another element to squeeze some more dmg from that buff.
To be honest, the only way I see this working is in rainbow, on a fat creature, using rage potion and maybe even SoR. Huge amounts of cards needed to be drawn in right order to pull off this combo. You'll probably better off with just playing another creature.