If you activate first, after activating any [When Attacking] or [When one of your Digimon attacks] effects, you activate the other [When Digivolving] effect before the counter timing occurs
But by that point, their dwindling mana pool will hopefully have given you enough of an advantage to win
Urza is also an infinite mana sink, and lets you play your whole deck with infinite colorless and just a few blue mana
However, some must have escaped the Pokemon TCG vault as there have been a few listings of the cards, which have all sold for over $425
and Speed I don't think it's difficult for me to say that this mechanic just isn't for Pauper in a broad scope
It would also have been available to cast off of Sunforger, and beaten out other similar spells as the de facto best in slot