Firstly, she taps for mana, and when that mana is spent on a creature, it enters with two +1/+1 counters on it - representing her literally summoning a powerful monster to the battlefield
Although the ninjutsu ability has the creature enter the battlefield attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example)
Also, if you are a very inexperienced collector, you may want to make sure that someone isn't selling you a proxy instead of a real card
Featuring a fan-favorite character is one way to propel a card through the charts, as indicated by the expensive Enchanted Elsa card from The First Chapter
Y'shtola was chosen for Final Fantasy 14 specifically due to the character's popularity and the fact that she's a spellcaster, though ideas were floated around for a highly customizable Warrior of Light commander, but they had "pretty in-depth executions." All of these sets will be released on June 13 later this year, and given how popular the crossover is probably going to be, you might be best circling that date in your calendar three or four times
I remember with the Baldur's Gate set, many of the important characters in the lore got shafted and were placed at uncommon to make way to promote Baldur's Gate 3