T1: Death Ring and Graveyard
T2: Harmonize (graveyard) and Skeletal Archer
T3: Harmonize (mage) and meditation amulet
From there, basically try to summon and swarm with as many creatures as I can get on the board.
I'd highly recommend dropping a Harmonize and trying this instead:
T1: Death Ring and Graveyard
T2: Deploy Skeletal Archer; Harmonize (graveyard) and do something else useful.
T3: Deploy a cheap Skeleton; quick-cast Meditation amulet; Meditate.
Otherwise you're paying 6 more mana to hopefully get more mana 9 turns from now. I'd rather have the mana advantage earlier than later. If you feel you really must have channeling of 11, then a Mana Crystal or Flower costs less than Harmonize on your mage.
Other comments:
- Drain Soul >> Drain Life.
- Deathshroud Staff is expensive for what it does (even with Death Ring). Besides, you don't really want to be close to the action, and you won't have many actions to spare when Meditating. You need to make every quick-cast count, and spending one to put on a weapon, then another to give melee +1 to creatures in the neighboring zone may not be the most effective use of your actions.
- Personally, I like to take full advantage of the poison immunity of the Necromancer and his undead horde; e.g. Idol of Pestilence, Plagued, even Poison Gas Cloud. This might mean dropping the bats and some of the more expensive skeletons... but your spawn point can't summon bats anyway (and you'll want to be Meditating, not summoning bats).
- Armory is better than Fortified Position, especially if you're Meditating; e.g. want as much bang for your buck out of those few quick-casts. Besides, you expect to be action deprived, not mana deprived, so you can afford quick-action conjurations in the 9-10 mana range (like Idol / Deathlock / Armory).
- Regrowth >> Vampirism (for your mage).
- I'm not convinced that you'll ever get 4x Skeletal Archers in play (not to mention 4x Skeletal Sentries and 2x Skeletal Knights and a Deathfang and Mort - that's a lot of expensive Skelies!), but if you plan to focus on the ranged attackers as your primary strategy, you'll seriously want to consider an Archer's Watchtower or two. The ranged +1 is always good, and Indirect can be invaluable to ensure they can get an unobstructed shot.
- Teleports and Force Pushes and Tanglevines are as fundamental to a swarm strategy as any other staples. Find room for multiples of these. Seriously.