Why is it never the "good" kind of tentacles?

Dumbledore "Champions! The task will begin as soon as the-*BOOOOOOOOOOM*... Cannons.. Nevermind the task has started! Go! You have an hour!" he shouts after sending a dirty look to Filch who simply shrugs with a nonplussed face at him.

Krum, Fleur and Harry all immediately dive into the water, however Ciri raises her staff and audibly casts "Accio Rusted Iron Ring!"

Immediately those watching feel a sense of foreboding, as if they were watching her executing of the dragon in the First Task again.

From the stands a run attached to Snuffles flies off towards Ciri who grabs it from the air and puts it on.

Ludo "It seems Ciri Rivia has found another loophole! What will this artifact do I wonder!" he exclaims.

Ciri doesn't hesitate and jumps into the water... He entry doesn't even create the smallest splash and she finds herself falling as if through air instead of water. He has to cushion her fall with a spell as she'd probably be seriously injured or dead if she hit the ground at that speed.

Once she's on the lake bed she casts the bubble head charm and begins a few movements to makesure everything is ok. She swings her staff like a sword and feels no resistance whatsoever, this ring is incredibly useful apparently. Nodding to herself she casts a point me charm and begins sprinting in the direction it indicates.

Those who were watching from the shore are baffled to see such an unnatural looking phenomenon, however they quickly lose her in the cloudy lake.

...

The audience stops cheering as soon as they realise that they'll be waiting there for an hour straight doing nothing... "Who came up with this!?!" a few shout. The only people enjoying the situation are Luna and Snuffles who are playing against eachother with cards...

Fleur had just entered the lake and wasted no time in trying to save her sister, the bubble head charm was quickly cast as she used small charms to boost her propulsion slightly. She continued doing this despite how weakly her magic was flowing due to the cold water around her, she felt it was needed but regretted doing it when she felt the presence of numerous eyes watching her.

"Grindylow" she mutters with feeling of dread overtaking her. Without warning she's immediately surrounded by them, she casts a couple expulsio charms at them which makes a few explode into a fine red mist however their numbers seem endless. They get close enough to where area of effect spells would hit her as much as her target, she cast a few wide Diffindo's that completely bisect a few and injuring more however she feels something bite her back. It's teeth sink into her flesh causing her to gasp and fumble the spell she was about to cast. Reaching back she grabs a slimy tentacle of the Grindylow that'd bitten her and pulls it away, inadvertently helping it tear a bite sized chunk from her back.

They don't let up however as she's besieged by more of them, they wrap their tentacles around her neck in an attempt to strangle her while a few try to burst her bubble head charm which luckily proves more durable then they can deal with.

As more and more pile on she can feel a few digging their teeth into her flesh, she struggles to try and get them off but to no avail as she mutters a soft "Sorry" for her doomed sister... However this isn't Game of Thrones, a Diffindo charm passes Fleur and manages to kill a large amount of the gathered Grindylows. Ciri who's been sprinting for a while now jumps up and slams her staff into a clump of them, knocking a few unconscious while giving brain damage to a few others. She pulls Fluer down to the lake bed so she can protect her more easily as without the buoyency of the water she's unable to reach such high places without using other means.

Fleur floats near the ground covered in many wounds which continuously leak blood as Ciri fends off a few more. Without the water resistance Ciri was easily able to swing her staff and react faster than these creatures could. They didn't stand a chance as she employed kicks, knees, elbows and any other move to strike at them. While their bodies resembled squids or octopi they had skeletons which were shattered with every strike of hers.

Once the water around her was tinted blood and littered with the many corpses of the Grindylows she turns her attention to Fleur who's still bleeding profusely from her wounds. It wasn't fatal but it would be if left underwater and untreated.

Ciri "Fleur can you make it back?" she quickly asks.

Fleur shakes her head, "Non! I need to find Gabrielle!" she exclaims.

Ciri "I'll get her for you so go back and get patched up, you can blame whoever made the task!" she says with no hesitation.

...

After a moment Fleur nods, and slowly swims to the surface where she'd be collected by the healers on standby.

Ciri watches her leave and quickly turns her attention to the task at hand, she takes a few seconds to catch her breath before starting to sprint toward the hostages again.