Won't Get Fooled Again

You know it, I know it, Sam knows it, everyone but Frodo knows. Sméagol will eventually turn evil and try and kill you. Unfortunately for him, that's what the heroes have been counting on. Getting tired of the constant hassle of beating Gollum into submission, they've just decided to let him stay evil. Glorfindel and Erestor start out keeping an eye on (and taking the resources from) Sméagol, but once Stinker is revealed, they happily go their own way in a perfectly serviceable two hero deck. The real magic, however, comes from the second deck, which extracts as many bonuses as possible from a 50 engagement cost enemy bouncing across the board every time.

In terms of strategy, the most important rule is to never flip Gollum back to his hero side. Beyond that, just let him go back and forth between the two decks, racking up bonuses all the while. To speed up Gollum's betrayal, the Smeagol Promised deck has encounter scrying/manipulation in the form of Risk Some Light, Firyal, Celduin Traveler, Ithilien Lookout, and even Shadow of the Past for if a copy of Stinker is discarded.

The Smeagol Lied... deck has most of the ways to benefit off of Gollum. Most obviously (and reliably) are the resource and card given by Mablung and Pippin. Beyond that, there's also Bywater Shirriff, which will always be boosted when Gollum's engaged, along with Raise the Shire to pull out any hobbits still hiding in your deck, though more often that should be played in the Encounter Phase. Also, when Gollum engages during the refresh phase you can play Expert Trackers, then ready the exhausted ally with Faramir's ability. Since this is the deck that gets the most benefit out of Gollum being engaged, I've also included three copies of Follow Me!, which can immediately pull him back over after engaging the other deck, reactivating all engagement bonuses.

In terms of deck roles, Smeagol promised is the more powerful questing deck, with most of the questing allies. With Light of Valinor and Strider both heroes should be questing without exhausting, leaving Erestor with a Cloak of Lórien to defend, and Glorfindel to attack. Smeagol Lied should function as the combat deck. Mablung is a very capable defender with Gondorian Shield, and Pippin with Hobbit Cloak can reliably defend Gollum. It comes with a full set of Dagger of Westernesse to give to Faramir and Glorfindel. The Bywater Shirriffs are nice utility cards, which can be used to quest or attack depending on the need.

While you could try and add other decks to this fellowship (Sam Gamgee, Tom Cotton, Halbarad, and Amarthiúl can all benefit from enemy engagement), I think it would only dilute the benefit given to each deck.