Funniest/most frustating way to play maokai suppoort, being an afk bot that spams E the whole game and sometimes goes all in.
This build is focused around 2 important stats, that maokai needs in order to works, those being hp, items with burn passive and CDR.

There's not much saying about this build, as it's not really something very complex, the whole thing is focused on his saplings to be as annoying as possible.
Their damage scales with ap, but the multipliers as really bad, and somewhat mediocre on his other abilities, so you don't really want to build much AP on him, just get liandry or mandate and demonic and that's enough for your DPS check. Every other item is considered based on it's other stats.

first of, while you definitely become more tanky, that's not the reason you want HP, it's not even about damage. The reason you want items like Warmog's Armor is to extend the duration of your saplings. When they are throwed in a brush they will stay there longer. With Demonic Embrace Warmog's Armor and Overgrowth stacked to 80 you get up to around 70 seconds of uptime.

Also fun fact for any builds, just by using Overgrowth alone you meet the condition to use warmog's passive, though that's unnecesary detail in this build as Demonic Embrace already provides the bonus hp needed.

Anathema's Chains is also a great item and second on HP values after Warmog's Armor, it will be especially useful if enemy team have only one main carry or just an enemy that is capable to hurt you. Also works really great with mao as it reduce the tenacity of that target enemy when he's near you, which is great since mao is traditionally an cc machine.

Spam E in brushes near enemies, or near objectives to control the map, think of it as playing shaco or teemo but enemies can't remove your saplings without risking being damaged .. unless they're very fast.

The cool thing is your range on E is pretty big so you can basically throw it straight into their turrets to delay more their retreat and things.

If enemies are low enough you can try to commit an all in, but usually just try to ult and clean if your team follows.
Also don't buy Imperial Mandate if you're not playing with a premade, and a aggressive one, this item loses a lot of value if your allies don't follow.

If you play with a Ivern them him where to place his brushes to have a good position for your saplings, they should remain empowered even if the brushes expires shorty after, so consider this if you wanna make the enemies think the sapling on lane is an innofenive one that will barely hurt them.

Those would be the basics.

Now specifically for lane phase, you only want to wait for it to end honestly, after some time or even from the start enemies will be wary of both your position and saplings so if you can't somehow bait or trick them then you having nothing to do except waiting for a gank and trying to poke them from time to time to get your gold. If enemies hit you too hard remember to use your passive from time to time to remain healhty.

At level 1 you could try to invade enemy jungle, but not in the direct way, either try a sneaky approach or a very extended trade one in which you just spam E in the brushes near them. Your E have a huge range so don't worry about toying with them a little before the lane starts.