The activated ability gives you options of lifegain, counters, direct damage to flying creatures, or even some mill protection
Card Size is Different Paper Quality difference and Paper Thickness, but this depends on the set too I think, because they may change the paper stock that they use depending on cost of materials you can also ask a Pokemon Professor, they may have insight into fake cards entering the market and be able to give you pointers in spotting fakes
For example, a card might have a low converted mana cost and be a mythic but it might be just a vanilla green creature with two power and toughness
10 Cynthia's Garchomp Ex 80/63 Super Rare - $28.08 The gold motif of the super rare cards looks even better with this Trainer card, with the gold outline of Cynthia hovering behind Garchomp as if guiding them to victory
Anyway, it's for decks that want to line up artifacts
You now have fourteen sources of each color, all of which tap for that mana on turn 1