So if enough -1/-1 counters are placed on a modular creature to kill it outright, say if your 1/1 Arcbound Ravager gets hit with a Black Sun's Zenith where X=2, then the creature will die
All hail the mighty armies of Caesars Legion
Additionally, if a player uses it after their Pokmon was Knocked Out, they can retrieve and attach a Basic Fire Energy card from the discard pile to a Pokmon and, after doing so, they can draw cards until they have six in their hand
So if I attack with a 2/2 and a 0/3 in a band and you block with a 3/3, I could have your 3/3 assign 1 damage to my 2/2 and 2 damage to my 0/3, so everything in my band survives
I'd estimate that this strategy leads you to the right decision approximately 90% of the time
As they come down untapped you can usually put that mana to use right away making your card only a one mana investment and as such a smaller tempo hit than most alternatives