Consuming Grudge is there to help you time the Skeleton Warrior Soul Skill to get a free revive at the beginning of a turn, it shouldn't be used until then or it will put you in an SP hole.
Depending on the speed of your opponent's file, you can open Shade, Pact, Ancient Zombie Lord for maximum SP effecency (but slow speed) or Shade, Pact, Pact (early Iczers on theh enemy's part will probably give you an advantage SP-wise long term, especially if you can time Nightwing right).
If the enemy is weak to one of you level 4's, you can try Shade, pact, LV4. for example, an enemy Revnant would be weak to Francis, while someone rushing out low level units might be weak to XXXX, and an SP generating unit (which requires the enemy leave loose SP in his SP pool) would be weak to Nightwing Wyvern.
There are basically three strategies to the file: 1) field quality over quantity -- high powered higher level units. 2) Slow the enemy down so he can't overwhelm your field before they can do their thing, and 3) Counter your enemy's specific tactics.
1) involves Swordswoman, XXX, Frances, and in the later game when his Action skill is actually useful, UK Zug. To a lesser extent Devil, but as long as he's got some tanks around him, with his Action skill he can last a long time. They are all capable of really tearing into the enemy file, with speed, damage and and special abilities. The units that need speed are super fast, and the ones that don't are super slow, so they're pretty effecient stat-wise.
2) Involves two parts, SP drain and tanking. Night Wing Wyvern's Open Skill, Living Armor's Close skill and leaving yourself open to an early Iczer bring the SP pressure. UK Zug, Living Armor and for the (very) end game, ZL Zug, all bring the tanking. Merc Death is also effectivelly SP drain, if the enemy fields a very high level unit.
3) This part is tricky, but once you get the hang of it will be invaluable. Crest Devil Knight can counter high AT hyper aggro tactics, and some field wipes. Francis is good agaist bigs, Undead, Lycans and counterskill units. Night Wing Wyvern can counter SP gen, late game UK Zug can counter some speed files, Swordswoman can use her Bash against units that are slow but strong, and her Bane against grim-dependent files. The whole file has some built in Falkow protection because it has no LV2 or 3 units.
"Scissors are overpowered. Rock is fine." -Paper