The synergies are all dependent on what you desire to achieve. I managed to sort them all in four categories: protection, attack, development and prison.
Protection
The Fox can grant a lot of protection, but there are times in which the protection itself it too little. In those cases you can use the following:
Circle of Protection: White -amazing thing. Not only does it cost so little but also doesn't actually target the source so even shrouded creatures won't do much as long as they are white.
Rune of Protection: White -same, except requires to activate.
Pariah -it works wonders as a damage preventer on indestructible creatures but can also work as a spot removal on opponent's creature. Joining it with Darksteel Mutation or using repeatedly with Sun Titan is nice.
Another one is Michiko Konda, Truth Seeker. Not really a damage preventer but certainly makes the opponent think twice before the attack or basically any damage.
Another way to avoid being hurt is not letting the opponent attack at all. Ghostly Prison does just that.
If the damage is already dealt and you want to heal, STOP! Hammertime! Loxodon Warhammer can be brought to the battlefield by almost every tutor in the deck and quite often be already equipped as well. So does the Umezawa's Jitte, Basilisk Collar, and, harder to cast or fetch, but still very handy True Conviction.
Lightning Greaves, Eiganjo Castle and Mother of Runes can help protect the creature/s that are already heavily equipped or crucial to maintain propitious boardstate.
Grand Abolisher and Nevermore prevent the enemy from doing too much, with Nevermore almost always targetting the opposing commander.
Attack
The undeniable core of every offensive strategy in here is the equipment so I'm taking the liberty to ommit it and instead go through the other cards that favour the attacks.
Elesh Norn, Grand Cenobite is a beast that does it all, but what's most important, she gets rid of all the little blockers opponent might have and shortens the rest while buffing her allies granting them safe passage during the attack.
Duelist's Heritage is a cheap version of Fireshrieker. Can't work if your creature has protection from white but that doesn't happen all the time.
Silverblade Paladin can make some mess! Not only doubles the damage, but also the triggers of the swords, which can be tactically equipped to both him and the paired creature to make them harder to block.
Kor Duelist is the man for the job. Fierce warrior not minding any obstacles, he can throw himself at any monster and actually live to tell the tale.
Armory Automaton is an artificial product that came to existence to fulfil the same purpose while stealing enemy's weaponry.
True Conviction can make any attack just twice as good if not more than that, killing the blockers in the first strike. All while healing the same double amount. It's really hard to perform a bad attack with it on board.
There are also the untargettable knights of valor:
Mirran Crusader
Fiendslayer Paladin
Kor Firewalker
Paladin en-Vec
They all serve the same purpose: to live and let die! ...and are tutorable with Recruiter of the Guard if needed against certain enemy.
Development
Provided a large boardstate this deck thrives in all its majesty. That's why there is so much ramp included. Enchantments, equipment, creatures and the planeswalker all take part in unifying and strengthening the wall I build before the enemy.
Therefore I include in this category all the mana rocks. Other cards really handy once they become a permanent include:
Inspiring Statuary -mana for free! (three, actually)
Vedalken Orrery -opens a LOT of options from casting every creature/equipment on flash to simply leaving all the mana untapped to react to opponent's moves and use all of it if willing in his end step.
Pearl Medallion isn't just a ramp. It also confuses the enemy with how much spells I'm able to cast on one turn since it's not just +1 mana.
Sigarda's Aid does help a lot. I'll never get out of the astonishment of how can such a powerful card have a cmc of 1.
Mentor of the Meek is a body for a potential sword itself, but also provides me with opportunities for card draw, which is very development-friendly and rare in mono .
Prison
Well, this is easy: Ghostly Prison, Nevermore, Darksteel Mutation, Pariah, Circle of Protection: White, Rune of Protection: White, Michiko Konda, Truth Seeker, Blinding Angel, Aven Mindcensor are all making the opponent slower and require more commitment and expenditure to do what he wants to.
Crib Swap is better than Stasis Snare simply because it does what it's supposed to -the exiled card remains exiled.
The Fox of course serves the same purpose.