Maokai is a great well rounded tank providing reliable cc and a strong aoe protection. A great farmer and is able to buy key items early on in the game.

Pros:

Strong reliable crowd control
Great range on the snare providing a good initiation skill
AOE damage reduction ult that provides return damage
Very tanky and can easily lead a tower dive fight
Good magic damage output
Great farming capabilities

Cons:

Runs out of mana easily early on, must make the decision to save mana for a fight or use it to farm and harass
Not as tanky early game

Magic pen marks give you that extra buff with your damage combo

Mana regen seals provide you with lane sustain

Magic resist glyphs give you that extra magic resist you lack from you initial stats

Health quints gives that extra tankiness in lane

This is my AP TANK mastery page

A good combination of damage and defence
The AOE reduction mastery points works well with your ult up
And the rest of the points in defence just mainly provide you with health amour and magic resist
The cool down reduction you get from the defence tree and the offence tree should be sufficient

Max your sapling toss first (strong damage)
Followed by your snare (utility)
Maxing your Knock back slow last (useful for its cc)

Putting a point in your Ultimate whenever possible

Star with a Dorans Ring, it will provide you with the mana regen you need plus bonus health and ability power

Purchase basic shoes

Build into a catalyst with a choice of more mana or health, choosing either of the crystal to your needs. After a catalyst upgrade shoes into merc treds, this will be very useful later on in team fights.

Next finish the Rod of Ages, at this point you are ready to initiate teamfights

The next item after the rod of ages is situational if the other team is ap heavy go with the abyssal scepter if they are heavy with ad go with the frozen heart

The aegis of the legion will work well with your ultimate

A guardian angel to finish off with your tank build

This Item build gives a good balance of damage and defence.

Any of these summoner spells work well with maokai:

Flash
Ghost
Exhuast
Ignite
Clarity
Clairvoyance

I just prefer ghost and flash to either escape or chase down enemies. Both these summoner spells also helps initiating a team fight which is the Maokai's strong point, (Initiation)

The trick to getting all your items fast is farming, with maokai farming is just too easy.

With a lvl 3 sapling toss aim the aoe right on top of the 3 caster minions the landing of the sapling and the explosion should give you all 3 minions in one shot. this method is great for farming early when your unable to get up close with melee hits.

^and... that's the trick :)

I learnt this from a friend, and wow this works well.

To initiate a 2v2 in lane fight try land a sapling on the enemy champion and immediately follow with your snare and your knockback slow. If you land this combo and your partner puts in some of their own hits or summoner spells this will grant a kill or even a double if they decide to fight you.

This is also the way to initiate other teamfights or tower dives.

That's it. Good luck with your Maokai games and I hope you find as much success with him as i did. Maokai truly is one of the best tanks.

"A fed tank makes a fed team"

^so true

Start a Wraiths drop your 1st sapling at 1:05. Drop your 2nd after cool down and drop your 4rd one with Wraiths spawn (1:40) give the blue wraith one hit and continue to blue buff
Finish Blue and start the normal jungle route spamming your skills along the way to get health back from your passive.

1. Wraiths
2. Blue Buff
3. Wolves
4. Wraiths
5. Double Golem
6. Red Buff
7. Wraiths again if you are able to continue, you could also recall or gank