Are alchemy cards rare? If they are, I guess they shouldn't be included in starter decks.
Aether should have 6 Lightnings and 6 Parallel Universes, instead of Quintessences in my opinion. Mono aether simply doesn't work without some stall, so since Phase Shields are rare, their only other possibility is to kill opposing attackers with lightnings while gathering quanta for Phase Dragons, PU, or fractal spark. Parallel Universes can be used as a counterweight to expensive Aether creatures - PU an opponent's dragon (if he dared to play a dragon deck) and you get some more damage, until opponent uses all his CC on it, due to no other targets. Other possibility would be to make use of your weaker creatures when fighting Aether players, thus forcing some variety in battles even with very limited low-level player's vault.
If gravity was to start without BH, they might have to start with some Catapults and Acceleration for example. If Catapults are going to be rare in WoE, then 6 Accelerations will probably be the best replacement. (Assuming Acceleration is added and works similar to EvaRia's idea)
Life without adrenaline would have to start with 6 Emerald Shields and 6 Empathic Bonds
Light without Luciferin - > 6 Blessings (some use for photons)
Time without precognitions -> 6 Hourglasses (I guess they are not rare right now, and shouldn't be since in unupped decks, with no possibility to go rainbow, and with no SoG and hard access to other stalling cards, Hourglasses are in fact a very weak, almost useless, card. No need to make them rare.)