Since the release of Meditate, Equilibrium has no place in ESO.
Equilibrium + Morphs
Equilibirum: Barter with Oblivion to trade vitality for power, sacrificing 6000 Health in exchange for 3000 Magicka. The exchange reduces your healing done and damage shield strength by 50% for 4 seconds.
Spell Symmetry: Barter with Oblivion to trade vitality for power, sacrificing 6000 Health in exchange for 3000 Magicka. After the exchange is complete, the cost of your next Magicka ability is reduced by 25% for 5 seconds. The exchange reduces your healing done and damage shield strength by 50% for 4 seconds.
Balance: Barter with Oblivion to trade vitality for power, sacrificing 6000 Health in exchange for 3000 Magicka. After the exchange is complete, you gain Major Resolve and Major Ward for 20 seconds, increasing your Physical Resistance and Spell Resistance by 5280. The exchange reduces your healing done and damage shield strength by 50% for 4 seconds.
After considering passives,Equilibirum costs you 5,100 Health to get 3,000 Magicka. It also increases the strength of your next light attack by 40%. The self damage dealt by Equilibrium is not effected by Battle Spirit, or any other form of damage mitigation. It also gives you +2% Max Magicka and 2% Magicka Recovery while slotted. This seems great, but is less useful because even if this skill was improved, it would still be a "backbar skill".
Meditate + Morphs
Meditate: Focus your body and mind into a meditative state, healing for 1518 Health and restoring 1518 Magicka and Stamina every 1 second. You will remain in a meditative state until you toggle this ability off or are interrupted.
Deep Thoughts: Focus your body and mind into a meditative state, healing for 1518 Health and restoring 1716 Magicka and Stamina every 1 second. You will remain in a meditative state until you toggle this ability off or are interrupted.
Introspection: Focus your body and mind into a meditative state, healing for 1518 Health and restoring 1716 Magicka and Stamina every 1 second. Maintaining the channel increases the Health restored by 10% every tick, up to a maximum of 50%You will remain in a meditative state until you toggle this ability off or are interrupted.
After considering passives, Meditate gives you Major Protection while channeled, a 5,000 damage shield while blocking while slotted, and each time it is toggled in combat it generates a charge, upon generating your fifth charge it will deal X Magic Damage or Y Phsycial Damage, whichever is higher to the closest enemy to you.
This is not a call to nerf Meditate, but a call to buff Equilibrium.
What use does Equilibrium have when compared to Meditate? Mobility. Meditate requires you to stand still, but offers protection, and no cost in return.
Suggestion 1: Half the cost and increase the return to 4,500. This might seem overpowered, but remember any Wards and Heals you cast are reduced by 50% for 4 seconds after the cast, essentially giving your opponent(s) extra burst potential.
Suggestion 2: Remove the "The exchange reduces your healing done and damage shield strength by 50% for 4 seconds" effect. You essentially pay for the 3,000 Magicka twice. 5,100 health, then 4 seconds of reduced self-defense. Removing the lingering effect would reduce the current massive cost to the ability.
Suggestion 3: Remove the Health cost. I don't think this is the right way to go as it'd break the "lore/description" of the ability. Nonetheless, it'd make the ability less penalizing to cast, and bring it more in line with Meditate.
These suggestions are meant to be individual "fixes" to Equilibrium, and not cumulative changes.
Also worth noting: The skill is outright bugged. Even with the cost reductions, which reduce the cost to 5,100 health, the skill is not usable until you are over 6,000 health.