So are the battle.net balance gift cards on Amazon.

Here's one review for those cards:

$20 Battle.net Store Gift Card Balance - Blizzard Entertainment

https://www.amazon.com/dp/B012JMS4W2/ref=cm_sw_r_cp_apa_i_L9IWCbQ4H17HJ

it should be noted these CANNOT be used for a subscription. you may buy a one-month game time with it, or pets, or mounts, etc. BUT NO subscriptions (the recurring billing option) nor can it be applied to an existing subscription.

If this is true, you can't get the discount you get from purchasing multiple months at a time, right? If that's the case it's less valuable because you're paying the full $15 for a month.

I've also read that you can't split a battle.net balance with another form of payment, so if you end up with say $14 you won't be able to purchase any game time with it.