Theres basically nothing better to sacrifice to powerful exploit cards than decayed Zombie tokens
Custodi Lich forces an opponent to kill something and makes you the monarch
It could be a way to knock counters, enchantments, or equipment off of a creature , or even to stop your opponent from comboing off of a permanent by temporarily removing it from play
Kaldheim brings with it new keywords such as Foretell, which allows you to exile cards from your hand to play them later for slightly cheaper, and Boast - which is a lot like the Raid mechanic from Tarkir, but this time around you can use special effects on cards for a different cost
Kalain is also the cornerstone of a new red-black commander deck being released with AFR , so while there will be a lot of copies on the market, shell be useful in a lot of decks
Having only two lands happens too often to have even a slight chance of not having the mana for that