(Until your next turn, that creature can't attack or block and its activated abilities can't be activated.) If a card has no mana cost, its escape cost is an unpayable cost, so you can't cast it for that cost
Both cards are instrumental in creature recursion combos, whether by creating extra turns by returning CoretapperCoretapper, or by creating an infinite combo by returning Saffi EriksdotterSaffi Eriksdotter or by returning Karador itself using Cadric, Soul KindlerCadric, Soul Kindler to create a copy of it, allowing you to cast it
Which makes sense, this is a card that gives you one token a turn and then its an anthem
If you're playing a deck that doesn't plan on attacking very much, it can climb you back to near 20 life with ease
These are probably the commanders who most inspired the good stuff piles of yesteryear but they wouldnt be the last
Some are alternative treatments of cards found in the Commander decks