Well, here goes.
1. Vanilla creatures or, preferably, creatures with a passive that rarely comes into play. (More Vanilla = Larger Card Pool and more variety overall)
2. Life Soft CC (Light has Holy Flash, so Life should have some soft CC too)
3. Time Rush cards (Probably the only thing they really really lack.)
4.Time More Active abilities expressing control over memory and time manipulation
5. Death Anti Holy Flash / Better hard CC (put these two together because I believe they can be worked together)
6. Aether Powerful Vulnerable TU worthy creature that has a Star Theme (we already have dimensional creatures and Immortal is Aether's Midsize attacker.)
7. Darkness Use the opponent’s offense against them mono. (Something weak but interesting)
8. Earth's new way to produce quanta. (prefferably cross element)
9. Water's New Weapon (something that can be used in a mono fairly well)
10. Air Soft Sound based PC (Again weak but interesting)