Repetitive flash is ridiculous, and would completely ruin any limited format in which it was printed. You could put it third from the top to be more fair.
Last resort could be printed, but probably shouldn't be given the power level of similar cards.
Artificial Knight is too good to see print, although I don't know if it would see much constructed play.
The low power level on that blue one is a bit jarring. How about
Mark of Esperness U
Wnchantment-Aura (C)
Enchant creature
Enchanted creature has hexproof.
As long as enchanted creature is white or black, it is indestructible.
Others are cool and fine color-pie wise.
Last resort could be printed, but probably shouldn't be given the power level of similar cards.
Artificial Knight is too good to see print, although I don't know if it would see much constructed play.
Conceptually speaking, these are all pretty nice.
If we really want a repeatable effect, I think T is probably safest without being ridiculous.
Mark of Esperness U
Wnchantment-Aura (C)
Enchant creature
Enchanted creature has hexproof.
As long as enchanted creature is white or black, it is indestructible.
Edit: That does allow you to draw 2-4 cards in the proposed scenario, just to be clear.
Edit: Didn't notice phantasmal on my first go through, can probably cost U for that kind of drawback.