You must pay any mandatory additional costs
Maybe a friend gave you a bunch of cards, or in those first couple of Drafts you got more cards than you know what to do with
If you put Otrimi under the Selkie, then the resulting merged creature is Cold-Eyed Selkie, a 1/1 creature with islandwalk and the Selkie's triggered ability, but also has Otrimi's trample and triggered ability
Force of Will You can cast Force of Will for 5 mana as an unconditional counterspell, but most of the time, youll cast it for free via its alternate cost
Rather than coming back as a flyer, the creature can come back as an Aura, often providing something reminiscent of what was on the original card, such as flying in the case of Lantern Bearer
Furthermore you get to draft pick the cards from the boosters and after the tournament add them to your collection