Ok. Heres the deal. For a start, your opponent has two treemen. In tournament he would be severely marked down for his compsition scores, because its basically just cheesy. The rest of his army is pretty
Additionally, the rest of his army is pretty fricking naughty. As in, pushing he boundaries of good taste.
That aside, heres how you do things.
Slann taking fire magic normally (or life if theres LOTS and LOTS of beneficial terrain ONLY). Give him cupped hands, focussed rumination, bsb and focus of mystery, and big unit of temple guard.
Lots of skink skirmishers (like 4-5 units). No cohorts.
Not more than one unit of kroxigors. They are able to be march blocked easily and don't move very fast.
Take engine of the gods. Level 3 priest. Use the area of effect damage ability as much as possible.
Take 2 units of saurus with spears 18 strong (ranked 6x3). Or another of the same size.
Take 2 razordons. They really really ream wood elves. No salamanders.
Don't be afraid to charge your skinks into their toughness 3 low armor save units. If they randomly break a unit, which honestly does happen, they will instantly make thier points back or more.
Don't take saurus cavalry. You may like them but do you notice how they get kited around and don't get to do much, even before they fail a stupidity test? Yeah...join the club. Its because they are worth lots of points.
Ignore the dryads when it comes to shooting and magic. Get the soft stuff
(glade riders, war dancers with war dancer noble, wild riders, spellsinger,spellweaver). Face the saurus off against the dryads. Use flee reactions at interesting times. Protect your razordons and shoot at toughness 3, non skirmishing stuff or single characters if at all possible. Deliberately block the movement of his combat units with razordons, goading them to charge so you can stand and shoot like a machine. Throw your skinks into the way, they there to die and draw fire so your saurus can move and so your slann can melt his small units. Keep the engine of the gods away from characters that can kill the skink priest in combat. The EoTG buffs your slann and can blast them with the aoe if he's alive. Hide him behind a unit of saurus if you need to. Yes, he can get shot but its in combat where he's properly vulnerable.
Bunch up your troops, except from the skinks. Trundle forward.
Feel free to put questions to me if you dont know why I suggested some things. I massacred a wood elf army yesterday. (To be fair, he only had on treemen, like a real human being would ;p).
Additional*Personal** I wouldn't play an army with shooting, magic, lots of skirmishers and two treemen.
If he told me that he can take whatever he wanted and that in effect army composition is stupid or irrelevant, I would take three units of 10 skink cohorts and 8 stegadons, and advise him to swivel on it.