TL;DR:
http://gw2skills.net/editor/?vhAQNAR8encfC9filpBufCEgilUjicAugAo8DSuupeZr2rF-TBBXgAAK/C1N0r+zjSQA-eGS/S/Shield, as much Zerk gear as possible, against dredge or boon heavy enemies swap Furious Interruptions for Shattered Concentration, and swap Gravity Well for Time Warp in Fractals. For PvP/WvW replace a well (probably Recall) with Decoy, and optionally shield with torch.
The gistHonestly, when I first heard about Chronomancer's release, I felt pretty lukewarm about it. I didn't want to give up one of the juicy specializations I used in my old Mesmer build, and torch was so good defensively. Turns out Chrono is a dream come true to play, and shield is even better offensively AND defensively than torch ever could be (for zerk). Here's why Chrono is the best thing ever:
1. F5 Continuum Split (it might seem complicated at first but read the tooltip and play around with it and you'll get the hang of it). Aww yeahhh, you can spam all your awesome stuff for free since you get all your fresh CD's back when you pop out... which might be a few seconds longer if it bugs and doesn't revert you back when it's supposed to. Anyways, you've probably figured out by now that you can double cast awesome spells like Gravity Well, but since you're all a part of this awesome guild I'm going to share the biggest Chrono secret: ALL of your skills have no more than a 90 second cooldown. "But wait," you say. "Time Warp is 180s CD!" The trick is to only use those huge abilities while you're IN continuum split, and don't use them until it's ready again. CS has only a 90s cooldown which is even less with alacrity, but we'll get to that in a bit.
2. Wells. Wells are, well, pretty damn awesome. Mesmer was already one of the best ranged damage dealers in the game imo, and now they got even better with some awesome AoE. I'll go over the specifics of wells in the skills section, but just know that they're good and you're probably gonna want to use them, especially since they give tasty Alacrity. Speaking of which...
3. Alacrity. It makes all of your skills recharge much faster, and generally it's pretty awesome. As a minor trait in Chrono each time you shatter you gain 3/4s per illusion in alacrity, your Well of Recall (40s CD chill well) gives 5s of alacrity, there's a trait you'll want to take that makes wells give 2s of alacrity when they end, the phantasm from Shield 4 skill gives alacrity around itself when it attacks, and that's about everything that generates it. Shattering only gives it to yourself, while wells are awesome for spreading the purple fiery love that is alacrity to allies who actually manage to stay in your wells when they finish (which they usually don't... oh well). As long as you pay attention to your wells, you can grab some extra alacrity to keep on spamming them skills.
4. Chrono traits. Some of them are amazing. The third minor gives you permanent 25% move speed increase, which mesmers have desperately needed for a while. The top row of selectable traits is PvP-related slow traits which are kinda gimmicky and imo you can ignore. Taking the bottom row is fine, and if you're adventurous you can experiment with the middle row, which has a focus on shattering. There are a lot of interesting ways to play, but like I said taking the bottom row is fine (it gives you the 2s alacrity for wells, 50% alacrity duration increase to you, and the most awesome... Chronophantasma, which lets you keep phantasms for an extra shatter. Very cool stuff)
The SkillsGreatsword is still the best weapon in the game. I'll assume you've played around with it and sword to know the hang of them. And fortunately, with shield there's way more reason to want to weapon swap and get in dangerous melee range!
Shield 4 is so good if you're under a lot of fire, which you will be in the HoT maps. A lot. It's a 2.5s block with a twist. Finishing the cast summons a phantasm that has a cool melee attack but really this skill should only be used defensively, since you can't keep attacking while using it. As long as you block an attack with it you can use the same skill AGAIN. Huuuuge block uptime as you can imagine. It will save your squishy zerker hide.
Shield 5 is also amazing. Really. It's a moving stun wall that grants you quickness when cast, to allies that touch it, and again when it comes back after moving for a couple seconds. Great CC, great offensive support, really this skill feels and plays amazingly. Greatsword is still the best but damn does it feel good to weapon swap as Mesmer now.
Well of Eternity: This is your new heal skill. Use it! It does have a 30 second cooldown which is the highest for Mesmer heal skills besides the signet, but don't fret. You'll be getting a lot of alacrity which will drastically reduce the CD of this skill. Plus, it heals 3 conditions on yourself and allies which is another lifesaver. Also, it's one of the few heal skills that come in 2 parts: an initial heal, and another heal after 3 seconds when it finishes. If you're low on health, you can actually Continuum Split, cast this heal and other skills you have available, and if you press F5 again to go revert before your healing well goes off, you get the end heal and can cast your heal AGAIN. Also alacrity. So good. Also, if you're moving and taking a lot of damage, cast this IN FRONT OF YOU; when in combat your movement will be slowed enough that you will be in the area of the well when it finishes. I use this trick ALL THE TIME in Dragon's Stand at the Blighting Towers.
Well of Calamity: The highest damage utility skill well, on a short 20 second CD. Also cripple and weakness. It's good. This makes mincemeat of Pocket Raptors and does respectable damage to groups of other stuff. With these damaging wells comes the trickiness of Chrono: you get the alacrity from your traits only if you're standing ON the well when it finishes. But if you're trying to damage enemies with it, that means you have to be right next to them and taking damage. Obviously, this is not always the best idea. Against a single mob or two, you might as well; sword is technically higher DPS anyway. Otherwise, be careful trying to get alacrity from wells you put on top of enemies.
Well of Recall: The other damaging utility well I use, 40s CD. It gives base 5s alacrity, plus 2s from traits, plus 50% from another trait. That's a ton of alacrity, as long as you're standing on it when it finishes. It also chills but whatever. It's tempting to spam this like the other damage well on enemies, but against bosses and in some situations it's probably best just to put it underneath yourself like your heal well. Alternatively you can use...
Well of Action: This only has a 30s CD, but gives 3s of quickness instead of 5s of alacrity. Up to you if you want to use this. Personally, I think stacking alacrity is where it's at. You could replace Well of Calamity with this if you wanted to be more supporty or something. Up to you.
Well of Precognition: 45s CD, 3s evade, and a stunbreaker. Bleh. It looks amazing at first, but even in PvP it's kinda lackluster when you can be using another well. It's CD is way too high, and you'd never want to use this in PvE. You want some invulnerability to rez allies? Press F4. You got it. I wouldn't bother with this.
EDIT: after playing around with this well (IN PVP) a lot I really love this. You get another stun breaker, 3 seconds of juicy evade for unrestricted bursting, and it can help you or allies secure a stomp. Combine this with the quickness on shatter grandmaster Chronomancer trait and you have a pretty sick combo. It's kind of annoying because the final "pulse" that gives alacrity DOESN'T give evasion, so you have to be careful. Had an annoying thing happen in PvP because of that hahah... as they say practice makes perfect.
Oh, and Gravity Well is already the best for putting on top of downed enemies in PvP, so using this well instead of Well of Calamity is a fine option I feel at this moment.
Blink: Not specific to Chrono, but still one of THE best Mesmer utility skills. Useful in every game mode for mobility and it breaks stuns. This never leaves my skill bar, except maybe in raids when you're trying to squeeze out every bit of DPS.
Well of Gravity: Ohohohoh, the big bad well to end them all. This is amazing, and completely broken in PvP. Abuse this while you can in case it gets nerfed or something. Also it's really good in PvE to chain CC mobs, especially when dual cast with F5 Continuum Split. But in Fractals you'll still want to take Time Warp for more group DPS.
Time Warp: Still the best option for support DPS in group content. Now that it also slows, it's tempting to put it on top of bosses to help break their defiance bar. If your party is all ranged, this might not be the best idea though. Just be careful.
The ConclusionIf you've read all of this, you're even more awesome than before. If people are really interested I can post a sample rotation against bosses, as in a good order to use your skills most effectively. But with practice you'll probably get to something pretty close to ideal. That's about it. Personally, I think Chronomancer is one of the best classes in PvE and PvP and pretty much broken, but don't tell too many people. We don't want to get nerfed.... ^^