Six of these would force your opponent to draw a maximum of 24 cards. Six phase shields also force your opponent to draw a maximum of 24 cards.
See where I'm going with this?
It's kind of a bad card as you excluded shields weapons and pillars. Time already has sundials and hourglasses, which can do what these can every turn. I would just drop the ability to target yourself all together. Reword the card so it says "your opponent draws up to four cards".
