Turn execution, order of resolution
Untap, upkeep, THEN DRAW. I had a instant spell that I could have casted on my UPKEEP phase... to kill my opponent ... then the draw phase!! Just cause you have no cards in your deck does not mean that you lose... you have to be forced to draw a card for the "loss of game" to take effect.

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DAC169#34537 commented
By default, Arena auto-passes priority on upkeep & draw steps. You gotta put a stop on your upkeep ahead of time if you want to do anything before you draw.
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Irza#80909 commented
this is a serious problem for turn resolution!!! I even tried to use the Ctrl button to turn my turn into "manual" function to control the turn resolution effect. Serious problem!! old cards with "Cumulative Upkeep" are very very real.. and are paid during the UPKEEP phase.... before draw phase. Even the simple instant spell of "gain 3 life" can be cast during the upkeep phase, to save your life..... this lack of "upkeep" phase is a actual serious game play issue!!!