Tags for STRATEGIES:

#Draw
#CheatDrop (put onto battlefield)
#FreeCast (Cast for free)
#Copy (CopySpell, CopyAbility, CopyPermanent)
#Recursion
#Tutor
#Removal
#ExtraTurn
#AddLands
#Manasink
#Protection (Crea, Perm, Spells, All etc to indicate just what it can protect)
#Utility: Providing lots of options. Implied on all Planeswalkers.
#Finisher

Misc. other shells:
#PhaseFires (ways to get fires off the field for a controlled amount of time to cast more stuff)
#Dungeon
#Upkeeps
#Channel (Fires Friendly Interaction, like channel)
#Landfall
#RingTempt
#Counters (Implied on all Planeswalkers)
#Pod

Tags for abilities:
#CastTrigger
#ETBTriggerName
#ETBTriggerGlobal
#Misc.Trigger
#Activated

Flagging cards that "care about" certain strategies or features
#CA:Leg. (Legendary)
#CA:Hist. (Historic)
#CA:Act. (Activated abilities)
#CA:Trig. (Triggered abilities)

#Copiable (Useful if copied)
#NotCopiable (Not useful if copied)

Some less obvious synergies/combos:

Gandalf the White: Tricky to wrap my head around, he's a complex card. But he's easily the best flash enabler for when Fires has been phased out on someone else's turn. The benefit of his doubling effect may or may not be that useful, but he's the best flash enabler we have.

Upkeeps: Additional Upkeeps means more triggers for Prismatic Bridge. Additional beginning phase has obious added bonus of untap and draw.

Phase Fires: The Pandorica and Immovable Rod are the most straightforward and flexible. The biggest drawback is the mana cost. Venser is a great option because it's free, but he can only be used on my turn without instant speed walker abilities, and even then Fires comes back at end of turn. Mistmeadow Vanisher is the most convoluted as it needs a means to tap (Esika doesn't get us there). But it really flies under the radar and isn't major target. Same issues as Venser where it takes two cards to really be useful and Fires comes back at end of turn.