For one, Delighted Halfling is a better Cavern of Souls on a creature because for one green mana, Delighted Halfling is a 1/2 Halfling Creature with the ability to add one mana of any colour to cast a legendary spell that cannot be countered
On the stack, a split spell that hasn't been fused has only that half's characteristics and mana value
Even just with rares and mythics, thats a lot of fodder to boil down to just 71 rares and 20 mythics that make up this set, so Id imagine theyre all really good cards
Put creatures in graveyard, profit
More Edge : Jonathan Zucchetti Jonathan is an Italy-based Magic enjoyer that has been playing, although with some pauses, ever since Mirrodin released
With flying and lifelink, it easily triggers its own end step condition, turning excess life into additional angels