To Spell or Dispel, that is the question...

Ciri "Can't I try to complete the task without your help?"

...

Reima gives her a look "Trust me Ciri, you'll not be comfortable in the Task without my help... I'm sure you can complete it without me but not without... Losses." he says.

Fleur "You know what ze task iz?" she asks confused.

Reima glances at the others while trying to come up with a valid explanation... "Um, I'm a seer... Yes, I get visions of the future, like Ciri sometimes does."

Harry "Then can't you just tell us about the task?" Hermione nods in agreement with him.

Reima "If I tell you it would change the future... Trust me when I say you don't want that to happen." he says only making them more worried about the task.

Ciri doesn't listen to his seer talk but just continues contemplating about what she wants to do during the Second Task. From what they can tell it's underwater, this is easily dealt with with a simply Bubblehead charm, the same charm Reima had used to let them explore the ocean together however that didn't extend to her combat abilities... They made them fight a dragon in the first task, it wouldn't be much of a stretch to send a Kraken at them or something similar.

Hermione "Ok... So you won't tell us what the next task will be?"

Reima nods, "That doesn't mean I won't train you in things that might assist you..." he says causing Harry to stand straighter.

Harry "Ok, what should I do?"

Reima smirks, "Ever heard of the Bubblehead charm?"

Thus the training for the three champions begun, he first started on getting them to master the Bubblehead charm as it was the most useful thing to use underwater. While it looks fragile it is actually one of the most durable spells around as it repairs any damage made to it before it can affect the caster. It's not like a regular bubble that will pop at the slightest touch, no instead it's like the "DeadPool" of bubbles, eternally coming back despite the damage it takes. Of course Ciri and Fleur already knew generally how to cast it but Harry? Not so much. Reima estimated it'd take around a month for him to learn and master the spell enough to be able to cast chantlessly so he can use it under water. The reason you need to use the spell underwater first instead of before you enter? Because the spell basis the strength of the bubble on the current pressure around you, it uses more magic to strengthen the spell if you are underwater when compared to air, thus allowing you to not drown.

Of course that wasn't all he was going to teach however, most spells wouldn't act the same underwater which can lead to unpredictable effects... Bombarda for instance would release a shockwave from the wand that would incapacitate everyone nearby, including the caster. How was this discovered? By a wizard in a swimming competition who thought it would give him a "boost", the Auror's were cleaning up bits of him for days afterwards.

The main spells he was going to teach that worked underwater were :

Gravis charm : Causes the weight of whatever it hits to increase ten fold. This would be useful stalling or even stunning things trying to harm you, it could also be used to quicken your descent into water.

Diffindo : Cutting charm, usually taught to be used on cloth or other materials however Reima had found it useful on flesh... The spell itself is taught to be cast as under-powered as possible to prevent possible misuse and injury. However when overpowered it'll cut clean through someones throat, belly or even bone if enough magic is used. Definitely a useful spell to use on underwater creatures.

Expulso : Different from Bombarda in that instead of causing an explosion at the first thing it impacts, Expulso sends out a bolt that causes it's target to explode. This deals incredible damage to whatever it hits and also releases a shockwave that can even knock people off of their feet. This is a dangerous spell to use underwater as if you are close by when it hits you may also be stunned.

These three charms while simple would be very useful for the trio, additionally Reima thought that Harry would be able to learn them all just before the task starts. Of course he was unsure about using such deadly spells but Reima noted he still had access to his other nonlethal ones, even if they might be less effective against underwater creatures.

After an hour or two Reima stops the class and has everyone attend their lessons as he and Ciri had some more Animagi training with Mcgonagall to do. Harry and Hermione leave after wiping the sweat from their brows and Reima gives Fleur a kiss before she too leaves.

Ciri "So you gonna tell me about your plan or do I have to wait like the others?"

Reima smirks, "You'll wait... I'd also suggest not trying to use any Pyromancy underwater... I might be immune to fire but I doubt your body could handle being boiled alive..."

Ciri nods, "Thanks for the heads up."

Reima waves her thanks, picks up Snuffles and starts heading to Professor Mcgonagall's classroom. Ciri doesn't look as excited as Reima feels right now as he can tell he's very close to finally reaching his form. Hopefully today would be the day.