Falin-Shaknah war

A conflict that has been going on for more than two decades.
Both sides insist the other side instigated the war. Several Magin traveled into Falin territory without permission, and they weren't discovered until they drew near to First Rock. Falin insist that the Magin disrespected the location and intended greater harm to it, but in truth the Magin were already on their way back from their goal. There is a lightning elemental housed in the caves below First Rock. Lightning magic is incredibly valuable to Magin as it's extremely rare and yet Magin almost-children are commonly aligned with it.
The trespass caused the Falin to grow extremely aggressive and territorial on the border between the lands. When the Magin came back to politely ask for access to the veins, trust was already broken and they were driven off forcefully. The Magin decided after that that the prize of a steady source of lightning magic was worth the effort, and confrontations began.
Wildlings reproduce faster and more reliably than Magin, and Magin are fairly frail in their physicality. The magic that they wield makes the odds much more even, but Magin hate 'wasting' magic by using it offensively when they could use it to have more healthy children. As a result, much of their battling has been stealthy application of a small amount of magic to do as much damage as possible.
In the 27th year of the war, the queen of the wildlings went to a seer to find a way to win the war for good. She'd already lost multiple children, and as she wasn't able to have any more children she wanted to safeguard those she had left.
She paid the price of her own magic for the rest of her life, but the seer gave her both what she wanted and what she needed. The seer told her that the way to decisively win the war was to 'corrupt' the Magin's source of water magic, which would make enough of their children starve that they would not be able to keep up. The queen was horrified, and instead she returned to the forests hellbent on peace between the races. Two generations of war had left their mark, though, and as part of the ceasefire they offered a precious commodity - one of their remaining royal children in marriage.
The marrying off of Euni solidified the treaty in which Magin are allowed access to the caves for lightning magic, but strictly supervised and in small numbers. Control of the territory stays with the wildlings, but they have little use for lightning magic and they can afford to allow the Magin to take enough.