Dim Shield
Sundial
Shard of Sac
3 strategies to balance it for.
3 strategies meets my suggested minimum for versatility.
I assume you used Dim Shield as a basis. However +3 turns on Sundial might be worth more than +3 turns on Dim Shield.
consider also the increasing synergy of Dim Shields in a deck. A Dim Shield/Sundial/Continue deck protects for 36|42 turns.