Competition for Cards: With so many collectors in one place, competition for rare cards can be intense
One of the tricks R&D uses is to put multiple cards in the same card code slot as a way to say "These cards cannot both go into the set so we're trying them out." This keeps the lead designer from constantly getting comments that the cards are too close
Theres also Drivnod, Carnage Dominus in the same vein as Teysa
Also, veterans of the "Pokemon Trading Card Game Online" will be able to port their decks to the new game as long as they use the same login information
This protection and flexibility of activating its ability ensures Skrelv, Defector Mite is put into many competitive Constructed decks
in cEDH, Blood Pet is often found in Krrik, Son of Yawgmoth builds as a way to net an extra mana for 2 life, but also sees a lot of play in Inalla, Archmage Ritualist and Ad Nauseam lines to rush out these expensive spells or aid in comboing off with other cards to win the game