Her ult is by most accounts a poor man's Depth Charge. Thorns actually made the same statement on IRC yesterday and it brought about that discussion. (The correct answer is actually Endless Rage but I digress.) It also made me consider how eerily similar Sejuani and Nautilus are, which is kind of a poor move on Riot's part considering they're one champion away from having been released consecutively. :/
Passive: autoattack trigger that helps keep the target from escaping
Q: mobility and initiator move
W: shitty AoE; nautilus' is actually a tank move at heart at least but even so it doubles as a shitty AoE
E: low-damage AoE slow
R: long-range AoE stun
They even have the same total AP ratios! Which kinda blew my mind when I figured that Nautilus should probably be built as tanky AP, yet pegged Sejuani for a tanky DPS build due to her low ratios. (That still has some merit: Nautilus has crappy base Attack Speed where Sejuani's is quite high.) If anything, it makes more sense for Sejuani to build AP since her W is a pure damage move where Nautilus' is shield first (which scales off HP), damage second. Either way, their damage is quite sub-par.
I mostly just wanted to point that out. 8) But seriously, Depth Charge stuns for the same duration as Glacial Prison and can also hit multiple targets... deals more damage, has a much shorter cooldown, and can't be blocked by a tanky frontline. The only notable advantage of GP is the longer range but even Depth Charge has a rather long casting range, especially for a point-and-click spell., that it's like complaining Caitlyn's ult doesn't have the same range as Lux's.
O.o I've heard the complete opposite; Depth Charge is a poor man's Glacial Prison. Depth Charge isn't that much of an initiation move, primarily because of how close you have to be. Rather, it seems to be most effective when you're already in the fight (no point in knocking everyone up just to have them be down when you reach your target). In addition, Sejuani can apply a huge slow to multiple champs without being close to them. Furthermore, imo a skillshot will always be superior when it comes to initiating than a targeted spell will. This is because you can afford to make blind shots, or catch people in bushes when you know they're there but can't see. Skillshots are usually supposed to be high risk, high reward skills, and in that regard, I'd say Sejuani's ult wins. I still believe that Sejuani will be stronger than Nautilus in a premade; however, Nautilus' CC is a lot more obvious to the random person. Your teammates can more easily register the target Nautilus chose because you can't ignore the giant anchor on your screen.
Sejuani is faster, has more health until they both hit level 18, has higher AD, base AS, AS/level, base armor, armor/level, base hp5, and hp5/level. And while she doesn't possess Nautilus' shield, she can cross walls and slow enemies without being as close as Nautilus. Honestly, Nautilus doesn't possess the CC Sejuani has. If anything, I'd say Nautilus is the more damage-oriented tank (keep in mind that his Q has a high AP ratio, his W has a DoT that adds up if you hit them over the duration, and his E should have a, what, 0.825 AP ratio if hit with all 3 blasts?), similar to Blitzcrank in that regard. Sejuani just won't have his damage, even if you went full AP. That's why she'll always be the better utility tank, imo.
But yet again, permaslows aren't something that randoms seem to pick up on as good CC. So in solo queue, Nautilus will seem superior because of his single-target disruption, his root passive, his non-skillshot ult, and his superior damage. Idk, Sejuani is the better utility tank imo; Nautilus can kind of do what she can, but with less emphasis on utility and more on damage.
