Okay, good, the Voidcaller WILL have "random" in its card text when it is released. The promo image of it they released did not, and they clarified on the forums that this will be changed. The wiki article also states it won't trigger battlecries. That makes it less OP in that you can't combo in a Jaxx hero, but more generally powerful in that you can bring out a Pit Lord or other powerful demon without suffering the negative battlecry. Still, less OP overall.
Here's a forum post on "random" wording rules.
Essentially, if it pulls from "hidden" space, like your deck or the opponents hand, they don't include the word random. because it's obvious you wouldn't be able to choose.
If it's something that you could possible have some agency in, like "heals another unit," they add random.
The exception is when they are faced with too many qualifiers, like with lightwell, and feel like random actually makes the card harder to understand at first. They're fine with players having to learn its random by playing it once.
They'll deviate from these rules wherever it feels appropriate to do so, but that's the general rule of thumb.
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IDrownFish wrote:
Anyways, you all are horrible, @#%^ed up people
lolgaxe wrote:
Never underestimate the healing power of a massive dong.