No "Upkeep" phase issue.
Actual problem, 100% I had the mana and a Perilous Vault out, 2 howling mines. It skipped by my upkeep and went straight to my main phase. If I had only 1 card in my deck I could have used the Vault on my UPKEEP PHASE, and destroyed my own howling mines to survive. or lots of other combos that could of taken effect. I didn't want to discard on my turn, so I wanted to use it... minor "want' but still if a different card did damage for discarding, it would of mattered.
3
votes

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DAC169#34537 commented
If you want to do something on your upkeep phase just place a stop on it prior to your turn.
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Irza#80909 commented
Guaranteed problem