When a Digimon digivolves, even if it happens due to an effect, it is not counted as an effect placing digivolution cards under that Digimon
In a go-wide deck it'll be particularly effective, since blocking a 1/1 token and paying mana or taking extra damage feels like a terrible deal
This versatility makes it easier to summon powerful Synchro Monsters, paving the way for formidable Blue-Eyes plays
Seven unique cards, each of which has a print run of 500
Too many low-cost cards and your deck generally wont have enough power to close out games (unless youve carefully crafted your deck that way), but too many high-cost cards, and by the time youve got the lands to cast them, youll be at zero life
They can easily just grind you out with Pyroblasts and Fact or Fictions instead of playing that one Humility in their deck