If you play something like Elves, Goblins, Humans, or Merfolk, you can fill your deck with 30 creatures of the right type and never worry about your mana curve because these creatures exist at all reasonable points in the curve, but if you ever play 30 Giants in a deck, then the average converted mana cost will be five and you will lose most games without ever casting a spell
Renet, Temporal Apprentice We highlighted this card in our best TMNT blue card guide, and even in the post-preview window, our feelings haven't changed
Gaining protection from everything can buy the player an extra turn, preventing all damage while also deflecting any spells or abilities that target players, from Thoughtsize to Lightning Bolt
With Collector Boosters, your players get direct access to the coolest cards from the set, with each booster packed with special treatments
One of the best cards for this is Leafkin Avenger, which lets you gain mana for each creature you control that has power four or higher, and use that mana to remove creatures or planeswalkers