When a human and a merson (mer-person) "pair off"-with a human as the rider, and a mermaid or merman as the mount-magic is involved. There's a connection that draws the two together. As time goes on, this magical connection grows stronger and comes with special effects:
The Beginning-Emotional connection (human and merson can feel other's emotions, distinct from their own unless they're feeling the same thing, in which cause the emotion is amplified) and telepathy apparent. The rider is light to their mount, allowing them to carry their rider with ease over vast distances. Additionally, the Gs and drag caused by or that should be experienced by the rider are reduced to negligible amounts.
Sprouting-Reached after the two have strengthened their bond and become in sync, perfect partners (like Ash and Pikachu). The rider gains a sort of secondary gravity that holds them to their mount, allowing them to use both hands without fear of falling off and minimizing the risk of being dislodged. The mount becomes faster, supernaturally so, as does the rider. They can fire streams of water and manipulate currents for propulsion and so forth.
Their movements are naturally in sync and coordinated (so the rider can take full advantage of their mount's momentum). If the rider did not have magic before, they do now. If they did, their mount's magic has grown stronger.
Blossoming-Only 30% of all Sprouted pairs can Blossom. In this state, the magic of both rider and mount is greatly increased (if the rider was a Level 7 out of 10 Mage and his ount was a Level 5 out of 10 Mermaid, they both end up at Level 35 out of 50); the two can create towering waves, whirlpools, and even icebergs. Massive manipulation of heat and cold (since water is an element of extremes, with steam representing fire and ice representing well, ice) is also possible for both. The life forces of both are bound, making it impossible to kill one without killing the other. This same synergy increases the base vitality of both and gives them hardcore regenerative abilities (think Wolverine, not Deadpool). As if that wasn't enough, 10% of these Blossomed Riders are elite, their mounts becoming capable of becoming a spirit of the sea itself: a dragon!
So, my question is: How would these riders affect naval warfare?
- Magic comes in four different forms: Evocation (Summoning), Elemancy (Element manipulation), Aethosynthesis (manipulating Ether, the stuff of magic) and Alchemy (Combining, Separating, and Transforming matter).
Evocation can summon things like whales or demons, but requires elemancy to function. As a result, evocation spells are doubly expensive, on top of being complex and hard to master.
Elemancy covers manipulation of all the elements; fire, ice, lightning, air, earth, metal, water, light, dark, and nature.
Aethosynthesis is used to form shields of magic or fire bolts of magic. Whenever you want to create something of magic alone, or even enchant something, you'll be using Aethosynthesis.
Alchemy is the magical form of chemistry; it can combine air and metal to cause oxidation or separate the atoms composing H20 to create hydrogen and oxygen. It doesn't work on living things or something in or on someone's person (your earring and stomach acid, for example, are safe). Alchemy consumes a lot of energy, and it can be countered by another alchemist (if Alchemist A wants to turn the water around a ship into hydrogen and oxygen so his pyromancer friend can light it up, he'll have to overcome the resistance of Alchemist B, who is blocking his efforts). Furthermore, it's easier to block alchemy than overcome it; helping molecules stick together when another alchemist is trying to pull them apart expends less energy than it would to pry them apart yourself.
As for naval warfare: This is fantasy, but things like steel ships and steam power exist due to the scholarly efforts of mages. In other words, it's still fantasy, just a bit more advanced. Sort of like Avatar: The Last Airbender.