If your spell got countered, youd still need to keep the sacrificed permanents paid for it in the graveyard
By phasing everything out, you'll dodge all the spells and abilities that could set your game back, and protect yourself from lethal damage for one turn
PSA, CGC, and BGS all allow you to look up the exact details and population reports of a card
The set appears to be absolutely loaded with fantastic cards for multiple formats
The same is true for flying, deathtouch, double strike, haste, hexproof, indestructible, lifelink, menace, reach, skulk, trample, and vigilance. In essence, your aim is to play Creatures with as many combat abilities as possible
These sizes are a good guideline, but they arent universal