While the "ease of flipping" category is, in large part, a product of the number of defense counters on the battle (battles range from three to seven defense counters, and a battle with three defense counters will be much easier to flip than one with seven), it also takes other factors into consideration, like whether the battle makes creatures (if so, we can use them to help defeat the battle, making it easier to flip) or whether the battle acts as removal (which can get a blocker out of the way, making it easier to attack and defeat the battle)
Creatures that have a cool ability that triggers when they enter the battlefield (ETB) can be found as far back in Magic: The Gathering s (MTG) history as Alliances , but Visions , released in 1997, was the first MTG set to truly lean into this area of card design
Otherwise, Squall might just appear in Commander
The value here is pretty high in reprints, but many of the new cards are narrow