That's come to be the colloquial meaning, but this card is actually pretty much dead on with the literal meaning.
The fact that it hits attack power as well makes it quite unique, so I actually really like this one.
I have 3 questions:
1) how will it interact with creatures that have negative attack power.
2) Will it be allowed to kill players / creatures that have only 1 hp left
3) Will it reduce current hp (like normal damage) or max hp (like shard of void)
My opinion would be to have it not be able to kill, but reduce max hp. Giving players access to a shard of void like effect without having to hunt down a very hard to find rare. Either way is pretty cool though.
Since 10% isn't horribly high, this should be pretty well balanced.
1) For example, if a creature has -10 attack, then 10% of -10 is -1, so the result will be -10-(-1)=-9.
The expression 'rounding up' is somewhat ambiguous when applied on negative numbers; if we round up 10% of -9, which is -0.9, then what should be the result?
Literally, if we round up -0.9, then the result should be the smallest integer not less than the given value, so it will be 0.
However, what I originally thought of is 'rounding away from zero'; I mean, if we round 0.9 and -0.9, then it will give 1 and -1, respectively. Which one would be better?
I also originally thought that 2) Yes 3) Current HP, but reducing max HP instead sounds a very good idea, giving synergy with Shard of Void.
I should consider it, as well as not killing targets. I think that if it reduces current HP then it may be lethal, otherwise (reducing max HP) it may not.