Fiery Annihilation
I had a mossborn hydra that was a 2/2 but had goldvein pick equipped which made it a 3/3. Opponent casted Fiery annihilation targeting my creature and pick. I casted a giant growth on it. The hydra had 1 toughness left but was still exiled. Lost me the game

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DanielStraus#02158 commented
Had very similar bug. Opponent cast Firey Annihilation on my Treetop Snarespinner (1/4). In response, I cast Giant Growth making the Treetop Snarespinner (4/7). When Fiery Annihilation resolved, it exiled my Treetop Snarespinner. However, it should only have done 5 damage (4/7 - 5 = 4/2).
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Rezzahan#77802 commented
2/2 base creature, plus +1/+1 from the equipment, plus +3/+3 from Giant Growth, effectively a 6/6. 5 damage to the creature, and reduction of toughness by -1 due to the equipment being gone, leaves a 5/5 creature with 5 damage, lethal, it would die, so is exiled. All as it should be.