So ive been using Ernie Ball Regular .010-.046 what would be a good gauge of strings to be playing metal, bands like opeth, slipknot etc...
Well, those two bands play in two different tunings, which are about 2 whole steps apart.
What tuning will you be playing in?
MESA 412
Try the ernie ball top heavy, light bottoms. The lower strings are larger, and higher strings are lighter. They're kind of good all around, for chugs as well as solos. If you're feeling adventurous try DR brand strings. They seem to last longer, and I've found them to be extremely comfortable.

Mick Thomson of Slipknot used Ernie Balls.
Daron Malakian of SOAD used Ernie Balls.
Kerry King of Slayer uses Dunlop.
Zakk Wylde uses Dunlops.
Trivium uses Dunlops/DR.
Steve Vai uses Ernie Balls.

All of these guys used impossible amounts of distortion at one point or another.
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Afterwards, Han Solo said "Great shot kid, that was one in a million!"
i was thinking of paying the extra for Ernie Ball Coated Electric Titanium anyone tried them?
Drop B, open D minor, but i still like to play some on standard and alot just a half step down, the Skinny Top/Heavy Bottom good for that
i love skinny top heavy bottom ernie balls. 10-52. i can go from a slightly tight standard to a very playable drop b (opeth - slipknot). so thats my vote. very good all round strings.
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