They're patching in line with what happened on Live as far as possible, I could try and dig through the patch notes to find the change but it'll be there somewhere. When that got patched in the mage population tanked quite considerably
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If you're a necro, pull the pet off at 20% or so and let your dots do the rest of the damage.
If you're a mage, I've seen mages reclaim their pet when the mob is at 10% or so, and then finish with a nuke. You'll need a lot of malachite etc but that's the way around it.
(or duo/group, the 50% doesn't factor in unless you're solo)