DonkeyHotep said:
If I were to try and bring down the tree man, I'd throw skinks at it, just skinks. If you REALLY are so worried about that banner then just replace it with musician and more skinks to hold more ranks for longer, and give you more initial poison javelins, just bring it to half health and you'll get enough VP to pay for the skink unit, not to mention skinks are innately useful against wood elves because they act as good fodder to absorb arrows, and the lack of rank bonuses means that just 25 skinks with banner and musician can hold up against things like dryads or treekin. (with toad helping especially)
Spirit of the Forge is by far the best way to kill him, he is a large target and you can see him everywhere. If he hides in a forest, why bother going after him? He isn't gonna do anything that has an impact on the game unless he gets treesurfed, in which case he must spend at least 1 turn to get out of the forest so you hit him when he sets up his charge.
Pit of Shades is another great spell, he only has In 2, so if you land a pit of shades on him chances are he is gonna poof, no saves allowed. The rest of the metal spells are far better against wood elves tho, so I still recommmend SotF.
Skinks aren't the best idea thanks to Strangelroot as I alraedy mentioned. They get 360 degrees stand and shoot, killing an avarage of 4-5 skinks. If your 15 big unit of skinks charge the Treeman you loose 1 rank on the charge and another one in the first round of combat. Then you're down to 8 skinks, which means you have outnumber and 2 ranks vs 2 kills in the combat phase in your turn, in his turn he clobberes 2-3 skinks, wins combat and is outnumbering terror causer, bai bai skinks.
A unit of 25 skinks can hardly hold up a unit of dryads. 6 Dryads get into combat, 12 attacks, 8 hits, 6.67 wounds and a 6+ save, killing 5.57 winning, which means they win most combats and you loose ranks very quickly (and soon 247 VPs). 4 treekins (the by far most common size) kills 6.67 skinks winning with 1-2 every turn, 2-3 rounds of combat and they break from outnumbering fear causers. When it comes to tanking wood elf heavy hitters Saurus is way, way better (even for if you count "per point") and can dish out some serious pain back at them.
In my experience there are 2 effecient ways to take treeman down, either by magic (SotF or Pit) or by just zerging him. Take a few turns to get everything into position, then hit him with Burning alignment, 36 skink blowpipes, giant bows, javelins, razordons and everything else you have and just hope you can blow him up in 1-2 turns of horrendoues mass shooting. If you try to take him down by chipping away at him, throwing a random unit of skinks now and then to blow pipe him, they will just end up getting killed by strangleroot or run off by terror.