Damage - Her target is dealing as much magic damage as she can in a small amount of time
Shield Breaker - A great secondary trait for a damage focused hero
Tasty - She's ambush spider bait
Reverent - Angel Dragon is able to resurrect her
Physical basic attack, magical skills
Hog Wild - Her white skill sends out a cute little hedgehog to give the first 3 enemies a nice hug. A hug that deals pretty respectable magic damage. Note that the range is a little weird. It's guaranteed to hit the first target, but it will only bounce to the next two if they are in range. If the target is too far away it's just a single hit.
Swarm - Lets loose a swarm of bees to damage targets in the cloud. Unfortunately, the cloud is rather small and will likely only damage a single target. Still, not bad damage.
Flower Power - This may be the oddest addition to her toolkit. This skill provides a "leaf shield" which is not actually a shield. Instead it provides an armor bonus to the ally with the lowest HP. This skill....is just strange. It'll usually target mages behind the front lines and instead of being buffed by larger shield runes, it just gives a flat armor bonus. If you were going to skip any of her skills it would be this one.
Good Vibrations - A skill that most mages would love to have. This passive reduces magical defense of the entire enemy team by a set amount. Always great to boost damage. I just wish the numbers were higher for it (for example, I have the skill at level 85 and it only reduces by 250).
Hedging Our Bets - This legendary skill MASSIVELY buffs your white skill. With this skill any target hit by your white gets their buffs removed. This includes shields, barbarian speed boosts, etc. For each buff that gets purged, the hog deals additional damage (from what I've seen it's pretty much like getting hit with the skill a second time) and the Druid regains a good chunk of energy. This lets her fire the skill more often, which causes more buffs to be removed, etc. A great legendary.
Ocean, Ocean, Ocean. All her best skills are based off skill power, so be sure to buff that up as high as you can. You could do bolt or river for faster energy gain, but Druid usually appreciates the damage more.
Barbarian - More attack speed means firing off your skills more often.
Dungeon Man/Cyclops Shaman - One of Druid's biggest issues is that it takes her a while to get started, the extra energy from these heroes really helps this out.
Moon Drake - Same as dungeon man, with the added bonus of an intellect boost.
Medusa - Once Druid fires off her skill, she is going to get back a LOT of energy, medusa helps her with the excess as well as providing a solid stun.
Shadow Assassin - With the exception of Swarm, all of Druid's skills are Piercing, meaning Assassin can boost her damage to weakened targets like crazy. A great pairing.
Ambush Spider - Druid is tasty, spider counters, end of story.
Ninja Dwarf - Ninja is going to take out this high intelligence hero without breaking a sweat
Cosmic Elf - Like all spell casters, Druid does not appreciate being silenced.
Void Wyvern/Bone Dragon - Druid has a hard enough time getting started, neither of these heroes help.
(+) Unparalleled at removing enemy buffs, severe punishment for buffed foes
(+) Can deal devastating damage to buffed enemies
(+) Good Vibrations helps out the whole team with improved magic damage
(-) On unbuffed foes, her damage is only okay
(-) Like all mages she's a little delicate
(-) Getting her first white to fire is a SLOW process. Great once she gets there but takes a while to build up