I never Harmonize Libro, and it seems hard to take full advantage of the action advantage offered by Graveyard and Libro at the same time. Death Ring Helps, but I can already cast 2 creatures/round with just Libro. I suppose I could use Meditation Amulet, but that doesn't seem efficient to get going when neither spawnpoint is a Battle Forge. It also seems extremely slow to get going for how much economy you get out of it.
Here are a few openings that I'm interested in using. Some I have used, some I've just theorycrafted:
Straywood Beastmaster
Aggressive
Turn 1 (19): Sprint to NC -> Battle Forge (11)
Turn 2 (20): Ring of Beasts -> Steelclaw Grizzly -> FD enchantment (1)
Turn 3 (10): Enchanter's Ring -> FD enchantment -> Pet Thunderdrift Falcon (1)
This sets me up for a decently powerful attack on round 4 even if my opponent stays in their starting corner. The 2 enchantments would generally be Bear Strength and Cheetah Speed, both on the mage, at least against an opponent that stays in their starting corner, but other options are worth considering. I would probably switch the Cheetah Speed into either Cobra Reflexes or Rhino Hide if my opponent was being more aggressive. I have some economy from Battle Forge and the rings, I can switch into swarm pretty easily if my opponent seems vulnerable to that, and I'm threatening 18 dice/round.
Johktari Beastmaster
Aggressive
Turn 1 (19): Lair -> Harmonize (0)
Turn 2 (9) [3]: Dire Wolf (0)
Turn 3 (9) [3]: Ivarium Longbow -> Shoot (1) [3]
Depending on my opponent, I will place the Harmonized Lair in either the NC (against aggressive opponents) or FC (against defensive opponents). I will then use the Lair to cast creatures, preferably Dire Wolves, although there are other options, in order to pressure my opponent and hinder them. I try to keep my mage 2 zones away from the action. If my opponent tries to chase my mage, I use Mongoose Agility, Tanglevine, Surging Wave, and Teleport to stay away from them while my animals tear them apart. If they fight my animals, I can hit them repeatedly with bow attacks.
Forcemaster
Aggressive
Turn 1 (20): Sprint to NC -> Battle Forge (12)
Turn 2 (22): Enchanter's Ring -> Steelclaw Grizzly -> FD Bear Strength (3)
Turn 3 (13): Force Ring -> FD Cheetah Speed -> Force Pull -> Reveal Enchantments -> Attack with Bear (4)
This opening lets me put a lot of pressure on my opponent. They'll have a tough time escaping the full attack from the Steelclaw due to Force Pull, and I'll probably play Galvitar turn 4 in order to ratchet up the pressure. Force Pull can either be used on the Steelclaw to pull it forward a zone or on the enemy mage to pull them a zone towards me. I would generally rather pull the opponent a zone towards me, since that sets up a Galvitar followup better, but if they play Eagleclaw Boots, I can still get my attack in during round 3. I don't tend to like openings that spend resources on guaranteeing an attack in round 2-3 (aside from Grimson rush), but Force Pull is a much smaller investment than Teleport or Force Push or especially Divine Intervention.
Warlord
Economic
Turn 1 (19): Battle Forge -> Construction Yard (4)
This is something you can do in every matchup. It gives you some economy, sets up a potential Barracks play, and gives you options for rapidly switching into defense. If your opponent doesn't put you under much immediate pressure, you'll follow up with something like this:
Turn 2 (13): Meditation Amulet -> Meditate -> Barracks (2)
Turn 3 (11) [2]: General's Signet Ring -> Orc Butcher -> Meditate -> Armory (1)
Against an aggressive opponent, you'll probably do something like this instead:
Turn 2 (13): General's Signet Ring -> Orc Butcher -> Wall of Earth (0)
Turn 3 (9): Leather Boots -> Goblin Slinger -> Leather Gloves (0)
Necromancer
Economic/Defensive
Turn 1 (20): Death Ring -> Libro (6)
Turn 2 (16): Venomous Zombie -> Venomous Zombie -> Leather Gloves (3)
Turn 3 (13): Venomous Zombie -> Venomous Zombie -> Leather Boots (0)
Death Ring -> Libro gives me a big boost to my economy extremely efficiently. I then want to get out all of my Venomous Zombies so that an aggressive opponent will have their creatures torn apart. This allows me to apply counter pressure against aggression. I would change this opening around against a mage that relies on Nonliving creatures or that didn't pressure me early, but I don't often see an opponent leave a Necromancer alone for very long. I like to get armor out earlier than usual with the Necromancer, as he is the squishiest mage in the game.
Arraxian Crown Warlock
Aggressive
Turn 1 (19): Sprint to NC (19):
Turn 2 (28): Lord of Fire (4)
Turn 3 (13): Dark Pact Slayer Blood Reaper
This opening is certainly not action efficient, but it does put your opponent under extreme pressure very quickly. The most efficient means of reducing the damage from Lord of Fire are Dragonscale Hauberk and Elemental Cloak, neither of which does anything by itself to stop the pressure from a Dark Pact Slayer Blood Reaper. Alternatively you could play a Mana Crystal turn 1, do something else turn 2, and then follow up on turn 4 or 5 with Dark Pact Slayer Blood Reaper + Rouse the Beast (there are many variations you can try like this). Often a Lord of Fire rush will get shut down if Adramelech gets killed, but that's not nearly as big of a problem if you already have a Dark Pact Slayer Blood Reaper down.