Earth DOES have a high cost spell, stone skin. It may not cost as much, but its limited use in the same way expensive cards are(if not more).
For death, I suggest a mass "Kill everything" card that sacrifices HP in addition to costing a lot.
I think high cost spells goes against the theme of life, life has a lot of cheap but easily castable creatures and a versatile spell set, so I wouldn't add anything to that. Besides, not every element NEEDS to have something like that. Mitosis kind of does the same thing functionally as an expensive card.
With the resent RT nerf, I wouldn't be against adding a "Freezing rain" style card to time. Cost 11: All creatures and perms on your opponents field are delayed for 1 turn, drain extra time quanta.