Kuku Mid S10

As I suggest you only take your movement ski at level 4 things can get a little hairy early game. You'll be dived and you need wards to help you know what is going on around you.
I find that 2 multis and one mana pot is optimal at the start as the health is nice but kuku is very mana intensive.

Don't be afraid to ult a wave if you have to. The first thing you need to do is get that book of Thoth.

It's no secret that book of Thoth and kuku passive synergise really well. So stack the book. You need to go out your way to Whirlwind (3) the center of waves then leave to go find jungle mobs or help at camp. Try not to take too much farm solo, but your pattern here is Wave then jungle. You want stacks fast.

This point you want Polynomicon. It makes your adorable sneeze (1) help you clear anything fast. Red buff? Easy, auto (3) auto (1) auto and it should be about done. Minion wave? Should be (3) auto soldier minion and the wave will be almost done maybe chuck a (1) just to be efficient.
Buy wards. Buy multis. That little bit of sustain is welcome and you can just chug em.
With these 2 books you already have around 450 power at level 10. Your poly basic attacks will deal around 240 bonus damage. This shreds through structures as well as god's. So get poking towers too.

Bancroft's and then Thypons... No one is taking anti heal...and if they are, well it still isn't good enough.
Assuming you're level 16 and have got both items your power will be a whopping 760. Your lifesteal at 42% and now you're substantially healing yourself.
Your autos will be hitting around 150 with the poly damage dealing an extra 400-450. Don't forget your (2) will trigger poly too.
At this point of the game you're able to stay around for quite a while unless you get mega dived. Ward up and don't be afraid to turn and fight. You'll heal almost half the damage you do that isn't bonus damage...and it's a lot. One whirlwind on a minion wave will heal you about 20% your health. That's without autos too.

I like soul reavers here. It helps against the non-squishies.
It takes our power to 900. This is usually the cap for other mages power but for kuku our passive lets us go over.
At this point you can tank a fire giant although you won't quite clear it solo but you have no fears. Good use of poly autos mixed in abilities helps you stay in lanes and in team fights. You can however fairly easily solo the gold fury. You won't need to ult it but if you wanted to clear it faster your ult will deal around 1700 damage so that last bit of health can go really quickly. You can't die to fury solo so if it's safe it's a good play.

The cherry on top of this build is the perfected rod of tahuti. The build lacks CDR% but it's fine. Hitting both abilities gives you a little speed up and a little CDR.
Your power will be 1013 and with a 500g power pot it'll be 1039.
If you get 2 poly autos off on pretty much anything it will die. Dash auto (1) auto it'll be dead. If it's tanky then it may need a whirlwind on it. Just remember you wanna hit them with your (1) and (3) for the cooldown and the movement speed helps you chase or disengage.

I hope this build is okay, it's my first time writing a build.
I've been having lots of fun with this build and it's been really funny to see people explode while I heal from their misery.
Try it out and let me know what you think.