You should always build tear on Gwen. Once you get to late or mid game, your mana pool will limit the choices you can make and you'll be relying on blue buff. The tear items give good stats and are worth their gold.

Demonic Embrace is a good choice if you don't know what to build. It gives you AP and a bit of defense in combat. If your looking to just build an actual defensive item, I would just build an actual defensive item then instead of Demonic Embrace.

It really depends on how much you find yourself fighting. On average, I complete mine in about 10 to 15 minutes. I recommend buying it early so your not trying to stack it 30 minutes in the game.

Thank you for letting me know your opinion. When I saw it, even I got overwhelmed by it but just brushed it off. I'll work on it.

The playstyles you do is dependent on your confidence. Lets say your in a good mood and your against an enemy laner you win extremely hard against like Darius. I would do the semi-aggressive strategy. If you just had a really bad game or/and your against a champion you lose hard against like Fiora, you should play the safe strategy. Aggressive strategy is the one I play the most, but I really don't recommend this to you. To play aggressive strategy effectively, first off, when you slow push the wave, your relying on hoping that the enemy top laner is dumb enough to let you kill them at least once. This will give you a gold lead against them which helps you 1v2 the enemy top laner and jungler. Second, you have to play flawlessly because if you screw up, you'll end up getting the enemy top laner or jungler back in the game or give them a lead. Third, you have to know how you can win a 1v2 against the enemy jungler and top laner 100% of the time. The third one just comes with experience and since I have over 100K mastery points on Gwen, I know how or can piece together how I can win the 1v2. Why this only would probably be the best in lower ranks like silver is because people have no wave management skills. It doesn't matter if the lane opponent has the best clear in the game. You are guaranteed at least like 10 or 20 seconds if you crash a big wave. When you crash your 2 or 3 minion wave, that's enough time to roam and take an enemy camp or two depending on your power. I only recommend roaming when your above 75% health because the enemy mid laner can help the enemy junger which will make it a 1v2 if they try to contest against you. If your below 75% health, you have a choice. You can go to the enemy jungle and drop a ward or two there and get out or you can simply just back, spend your gold, and slow push the wave again. The point in the aggressive strategy is to spread your lead around the map as quick as possible to end the game. The main reason this works in low elo though is because it win the 20 minute aram that happens. With your lead you'll completely destroy the enemy team if you play it out right. This typically leads to a surrender and if they don't just keep your lead by farming and taking objectives. Even if the 20 minute aram surprisingly doesn't happen, you can ping and take the baron with your team for free then proceed to end or take a couple towers. (People in low elo will listen to you more often if you have a positive KDA!) I will have to add this stuff in the section so thank you for asking.

I really recommend playing the Semi-Aggressive strategy and safe strategy. It's just safer, smarter, and allows you to scale freely at a good rate. The aggressive strategy is high-risk, high reward, so if you think your able to pull it off, do it. Also I know that cull only works on wave minions. 15 minutes is enough to finish your cull if you have proper wave management and cs well. You can probably finish it in 10 minutes if your really good.

The main reason of why I didn't include Everfrost and Hextech Rocketbelt is because I feel like Riftmaker and Night Harvester get the job done better than both of them. Everforst, yes the stun is useful for locking targets down, but if you miss it, or the squishy builds a stopwatch, that's it. Her Q and Everfrost isn't enough to kill the squishy anyways. You'll need your ultimate and a couple more autos. You can easily hit your Q's and other abilities without Everfrost so that's why I didn't include that. Hextech Rocketbelt is nice for the MS and extra dash, but Night Harvester will help you do the exact same thing. I put Night Harvester instead of Hextech because it was the second best. You don't need the extra burst, you just need to survive to do that burst. The extra ability haste allows you to do more Q's which is just more damage and healing. They both accomplish the same thing, but the mythic passive for Night Harvester is just better.

Cull is nice and is just as good as Doran's Blade. The additional gold you get is too good to pass up though. Your typically just farming for the first 15 minutes and that's enough time to get 100 CS if you cs well enough.

I put those options there so people can decide what to build. If they need a defense item, they can look at the defensive section. If they think they're good they can build a offensive item. In my opinion, its good to at least build one defensive item. That should be enough. If you need another defensive item to stay alive, just build another one. I just listed the best ones for Gwen. :D

Manamune is basically a substitute for Nashor's Tooth. You don't get all the damage you would get from Nashor's, but you do get the mana to sustain yourself. Archangel's is included because it gives you mana and gives you a decent amount of AP. Archangel's scales extremely well into late game and should be bought if you think that's where the game is going.

The reason I put Illaoi that high is because you will struggle to trade with her. She can practically farm safely all game if she wants to. As soon as you try to engage her, she can just back off, then poke you down with her E. If she plays aggressive though, she will be easily beatable.