They have strong sizes to casting cost, a strong ability when they are on the battlefield, and when they die they turn into their Temple, which taps for their mana and then heads back with a tap at sorcery speed but with a harder to do activation
The idea is that each set will have a specific card that will be the card that you want to pull, and a card with chase variants to look for
Lifeline Be sure you understand the oracle text on Lifeline
No matter where youre from, youve probably enjoyed some form of Pokmon media
Top (CTRL to add secondary) 3
Obviously the spread isn't the same on all cards (this is especially true of low-value cards), so the way you come out ahead is trading ten cards that retail for $1 (but sell for $0.50) for one card that retails for $10 (but sell for $7), or by trading three $50 cards that sell for $35 for one $150 card that sells for $120