Discard and Dominate

These two decks compliment each other beautifully statistically, thematically, and mechanically.

Statistically, the Spirit deck is a questing powerhouse with so-so combat capabilities. The Tactics/Lore deck is a damage-dealing machine with iffy willpower. Both naturally play very nicely with each other; the only overlap in terms of uniques is 1 copy of ally Háma, who is easily replaced with a second Will of the West. The only other common card is Elven-light, which means if the Spirit player can make do with two, (or if the Tactics/Lore player is willing to rely on reshuffling his deck and can forego the Elven-light entirely), both decks can be built from a single common card pool. Both decks start at moderately low threat, which lets them dictate their own pace, (as opposed to pairing with a high-threat deck, which often necessitates a quicker engagement).

Thematically, both decks rely on drawing huge amounts of cards, most of which will wind up in the discard, and then strategically recurring them. Whether it's Caldara pulling back Spirit allies or Háma pulling back Tactics events, both decks thrive on throwing their best cards at the encounter deck over and over again.

Mechanically, each deck synergizes well. Éowyn gives the Tactics/Lore player another outlet for unusable cards. Erestor and Elf-friend give Arwen another target for resources. It's hard for an Erestor player to make good use of Will of the West, since he might draw it early and be forced to discard it; the Spirit player has no forced discards, so he will always have one at the ready if the Lore/Tactics player missed something important and wants to run through his deck again. (Aside: as crazy as it sounds, this frees the Erestor player up to include even more card draw- Daeron's Runes, Deep Knowledge, etc.)