Why all this speculating? Let's do some theorycrafting!
Ziggs:Ziggs is, while entertaining, actually a very simple character. He has 4 AoE damage skills and is a burst caster. That's about it. Off the bat, we know he has good range just under Xerath (which is kind of annoying) and his cooldowns are a bit ridiculous (18 seconds? 16 seconds?). But he's a burst caster, so honestly all we care about is the 1 second damage potential.
Keep in mind... Ziggs is actually the only mage in this game with 4 AoE spells (and with the exception of Shyvana's Dragon Form, the only champion period). What this means for the analysis is that really, there's no real existing champion to compare him with. His damage potential will be a lot higher than others. I'll elaborate more on this after the analysis.
Passive: Short Fuse(Innate): Every 12 seconds, Ziggs' next basic attack deals 13 + (7 × level) (+0.35 per ability power) bonus magic damage. This cooldown is reduced by 4 seconds whenever Ziggs uses an ability.He basically gets this once every 12 seconds in lane (about 2 - 3 last hits) and about twice every teamfight. His range is 575, which is pretty goddamn high. So chances are he can easily hit you with them. A pretty good passive. Basically like fighting a very irritating Caitlyn. The damage itself is about equal to Lux's passive, except without the need to hit anyone with anything. More fuel for "Lux made even more redundant!!!!" *cough cough cough*
Q: Bouncing BombCost: 60 / 70 / 80 / 90 / 100 mana
Cooldown: 6 / 5.5 / 5 / 4.5 / 4 seconds
Magic Damage: 75 / 120 / 165 / 210 / 255 (+0.65 per ability power)This skill, damage-wise, is remarkably similar to Annie's Disintegrate, except AoE. Here...
Cost: 60 / 70 / 80 / 90 / 100 mana
Magic Damage: 85 / 125 / 165 / 205 / 245 (+0.7 per ability power)
Except Annie's is fixed at 4 seconds. Annie's range is 625. This one is 850, the same as Xerath. From what I've seen, it's pretty hard to miss this but we all know Annie's Q isn't the most amazing thing in the world. It's a staple spell. A lot of caster Qs are like this. They're merely there to be an "always up, so I don't feel completely useless" skill.
W: Satchel ChargeCooldown: 30 / 27 / 24 / 21 / 18 seconds
Magic Damage: 70 / 105 / 140 / 175 / 210 (+0.35 per ability power)1000 range. That's the same as Xerath's Mage Chains when he's in siege mode. So yeah, pretty far. Damage.... kinda meh. Scales really badly too. It's a knockup though. Don't think any mages of knockups so far. Delayed too, so he could really piss off some people... like say... Fiddles. The cooldown is pretty ridiculous though. 30 at level 1? And you don't max this till last? Oh god... better hope you don't need to use this to escape. Hell, even at 18 seconds I don't think you'd have the chance to.
E: Hexplosive MinefieldCooldown: 16 seconds
Cost: 80 / 90 / 100 / 110 / 120 mana
Magic Damage from First Mine: 40 / 65 / 90 / 115 / 140 (+0.3 per ability power)
Magic Damage from Additional Mines: 20 / 32.5 / 45 / 57.5 / 70 (+0.15 per ability power)
Slow: 20 / 25 / 30 / 35 / 40 %Oh ho.. now we're getting somewhere. This skill tells me this is where a good chuck of his damage will come from. The AoE is fairly big, and I know if you land it right (not hard), people have to blow up somewhere around 7 of them to get out (pray you're not Cho'Gath). That's what? 500 damage or so. Pretty good scaling too. That's a big amount of damage for just a regular skill. A pity about the cooldown though...
R: Mega Inferno BombCooldown: 120 / 105 / 90 seconds
Primary Magic Damage: 250 / 375 / 500 (+0.9 per ability power)
Secondary Area Magic Damage: 187.5 / 281.25 / 375 (+0.675 per ability power)This is actually really hard to place. On one hand, getting hit by the primary damage is... wow... ouch. It'd be the same as getting hit by a really powerful Tibbers. But if you get hit in the secondary area then well. It's kinda meh. Especially for an ultimate. The cooldown is 90 seconds, not too bad for a big ultimate. But yeah, you're going to want to hit that bullseye.
Conclusions:- Alright, we've seen that his damage is mostly okay-ish. Not bad, not incredible by any means. He's got decent range but no stun (big deal for a burst caster). But remember the AoE thing? This means that in the right situation... at the right time, this guy could easily put the hurt on an entire team if they're not careful. Got a Galio on your team? Then this is the guy you want. Because even though his damage is okay-ish... They can all x5, which becomes pretty crazy if you think about it.
- His cooldowns are really, REALLY long. That W especially. 30 seconds at level 1 is crazy and there's no way you're maxing that first. That's also his only CC spell and it's a puny, unreliable knockup. If a jungler or laner can force him to use this early, he's basically screwed. CC is extremely important for a burst mage. Can you imagine if Annie or Xerath didn't have stuns? If a caster doesn't have good CC, he'd better have something else going for him. Looks like Ziggs traded it in for his 4 AoE skills.
- Everything else seems kinda standard. His base stats are slightly better than the average mage but he has lower mana regen (probably won't be a problem considering his cooldowns). His movespeed is also pretty low at 305.
Tl;dr: Ziggs is a standard burst caster that has amazing damage potential if he can actually hit more than one person with his skills, long range, and ridiculously long cooldowns. Kill him in lane by forcing him to use his W. No reliable stun either means if you reach him, he's probably dead. Course... Sivir has no reliable stun either so it *sounds* way easier than it probably is.