I love the card. I have just had a difficult time protecting it from getting killed after only 1 use. I think it is best deployed when you have accumulated 7+ mana so you can play the card, use your hero power, and hopefully lay down a taunt minion.
That's a big beefy minion with a lot of ability to control the board. I wouldn't count this guy out. Decent with Elemental Allies, hard to remove, and decent effect? This could be a decent bridge between turn one and the mid-game for and Elemental type Mage.
I wrote my comment after only reading the first few comments. Your point is very valid and interesting. You spend 1 mana playing the sidequest and then at 3 you already have one elemental. Buid the deck such that you are very likely to have an elemental to play on turn 2 or turn 4.
Arcane Amplifier is 3 mana and is a very beefy 5 in defense. I would estimate that, on average, you should be able to get off 2 hero power uses so that is 6 damage total + the 4 damage in attack from the miinon...not to mention the damage your hero is not taking since this minion is attracting all the attention. 10 damage on average and 5 average is most worst case scendarios....playable for sure.
If you can hide it behind a taunt, play a spell to buff it or respawn it....I think this will be a really fun card!