So let's head back to the northern reaches of Europe with today's question: We know about Odin, you've talked about Merlin, think you could say a few words about Väinämöinen? Totally, because Vainamoinen is awesome and cool!
Vainamoinen is one of the most important gods in the Finnish pantheon. Born to the goddess Ilmatar and the personified sea at the beginning of creation after gestating in her womb for over seven hundred years (and thus becoming the most wise being alive), he was the first to find dry land and call upon the other powers of the universe to make it habitable with vegetation and life. He's not primarily a creation god, however; he is the lord of poetry and song, both of which were very important to ancient Finnish religions as the vehicles through which sacred chants and stories were preserved, and which grant him the power of spells over all who hear them, including the earth and sky themselves. Because of his combined prowess in making things and performing transformative art, he is one of the most badass of all gods of craftsmen. He's usually depicted as very old in order to drive home how wise and wizardly he is, although especially old Finnish art sometimes shows him beardless and presumably more youthful.
Stories of Vainamoinen's exploits are almost always adventures in creation that accidentally gets out of control. When the world is just beginning and Sampsa, god of fertility, has sown all the seeds upon the earth so that it can begin to grow plants, Vainamoinen noted that the only thing that was not growing was the seed planted for a giant oak tree, which was to become the World Tree of the Finnish universe. He dithers about this for a few weeks until Turso, terrifying walrus-god of the sea, appears on the shore and re-plants the acorn, this time using ashes from burnt plants and his own waters to fertilize this. The tree then grew perfectly - too perfectly, as it turns out, since it became so massive that it filled the sky, clogged up all the clouds, and permanently obscured the sun, moon and stars from the view of everyone on earth.
Now not quite as pleased with his tree plan as before, Vainamoinen calls on his mother Ilmatar to help him figure out how to uproot it so that life can start going on down on earth again. Because Vainamoinen bemoaned that there was "no giant" who could cut down the tree, however, Ilmatar sends him a tiny hero made of seawater approximately the size of his hand, which is somewhat discombobulating for him. Vainamoinen then has an argument with the little guy, in which the hero insists that he is divine and sent from the sea deities and can totally handle this, and Vainamoinen says a lot of variations on "But you're... really, really small."
Luckily for Vainamoinen, the sea-born hero then suddenly grows massive and goes to town on the tree, knocking it down and making all of its parts available for the creation of magical charms and weapons. Vainamoinen somehow gets most of the credit for this, probably because he called up the axe-bearing hero (who thereafter disappears) and also as the god of creation and words, goading a tiny person into becoming huge and taking care of business so new things can be made is sort of in his wheelhouse. He then went on to chop down all the trees in the world (the normal-sized ones) except for the birch, which became sacred and was spared so that birds would have somewhere to live, the better to have empty fields suitable for inventing agriculture in, which he does with magical barley seeds so that humanity can eventually eat.
In another story, we get a good old-fashioned bard-off when talented divine minstrel Joukahainen hears tell of Vainamoinen's incredible singing and poetic abilities, and decides to go challenge him to decide who the best musician truly is. His parents, especially his mother (who is smarter than anyone else in her family, apparently) try to discourage him, pointing out that Vainamoinen is also a super powerful magician who is going to totally ruin Joukahainen for being presumptuous and that this is a terrible idea. Joukahainen is having none of it, however, and declares that he'll beat Vainamoinen so hard that he'll turn his rival to stone with his wicked awesome lyrics.
Vainamoinen is just driving his sled around his home country generally minding his own business, so he's somewhat surprised when Joukahainen comes driving over the hill, literally causing sparks and fire from his speed, and intentionally rams him so that both sleds and horses are tangled up together, apparently on the theory that Vainamoinen won't be able to leave without participating in poetry combat first. Vainamoinen is peeved and yells at Joukahainen for his terrible driving skills, and Joukahainen demands to know his heritage, which mostly just makes Vainamoinen say the equivalent of "You're basically a baby, don't challenge me until you reach puberty, please."
But challenge he does! Joukahainen declares that he's much wiser and better and barding than Vainamoinen because age doesn't matter when it comes to talent, and demands, literally, a "war of wizard words." Vainamoinen responds by basically saying, "I mean, you challenged me so this is happening, but you're going to lose so hard."
There is much trash-talking, with Joukahainen suggesting several themes for the contest and Vainamoinen making fun of all of them as inappropriate, and then Joukahainen demanding that they just fight with swords instead and Vainamoinen refusing because he's not here for that, and then finally Vainamoinen starts busting out his awesome verse after Joukahainen is reduced to calling him a coward just to get him to participate. And since this is a wizards' duel, by the time he's done Joukahainen has already had his feet turned to stone by the power of the song, and takes a moment to reflect on how his mother kind of warned him about this.
Joukahainen then has to spend quite a lot of the story trying to come up with a bribe to get Vainamoinen to un-stone him and let him go home; when just praising Vainamoinen's powers and admitting he was wrong to challenge him doesn't work, he tries offering him magic weapons, magic boats and magic horses, all of which Vainamoinen says he already has plenty of because he can just make those things. Then he tries more old-fashioned bribery subjects, including gold and land, which Vainamoinen doesn't even really bother to refuse properly because he's pretty sure he invented those things in the first place. Finally, in desperation, Joukahainen promises to give Vainamoinen his sister Aino as a wife, and the old magician agrees and lets him go home to get that moving.
Joukahainen has clearly not gotten any better at figuring out what his parents would tell him to do, because he goes home weeping and wailing about the trade he's made only to find his mother, who had always secretly hoped Vainamoinen would marry her daughter anyway, saying, "Shut up, fool, that's the best possible marriage your sister could ever have, start planning the wedding already." Unfortunately, no one asked Aino, though, and like most women unfairly handed off to old men with no say in the matter, she is not thrilled by the idea of marrying a decrepit old stranger just because her brother can't handle his impulse control problems.
After refusing her mother's attempts to console her and convince her that this is really a good match, Aino goes out to do some chores in the woods, where Vainamoinen shows up and absolutely proves all her misgivings correct by being a creepy old man who pops out of the trees and tells her she's pretty and should wear pretty things for him. Because she is not about to be the victim of harassment in her own woods, Aino takes off all the pretty flowers and jewelry she was wearing, throws them on the ground and tells Vainamoinen she refuses to have anything to do with him. At home, her family tries again to convince her that she should totally just deal with being married to Vainamoinen, in spite of her protestations that she doesn't want to be enslaved to an old man who creeps on her in the woods for the rest of her life, and they stay on her case so long that eventually she gets fed up, goes to the shore, and swims out into the sea until she drowns.
Vainamoinen eventually hears the news when the voices of nature and the animals repeat the story, and thus learns a valuable lesson about hopefully not being a huge jerkface to the next woman he is interested in. He's pretty upset and not about to let the situation rest there, however, not with all these cosmic powers he has, so he boats out to where Aino died and goes fishing in an attempt to find evidence or comfort in the area. There he catches a magical salmon, which turns out to be Aino reincarnated or in another form, and is pretty irritated when she makes fun of him and asks him if he wants to go ahead and get a marriage bed set up for her to come be a fish in. She also says that she is transforming into a water spirit, like the other female water nymphs in the area, but that since the second time she met him he tried to gut and eat her with a fishing knife, he has really blown all the chances he could possibly have had with her.
Vainamoinen is generally pretty terrible at interpersonal relationships, so this is not the last time he will prove that he is awesome at cosmic magic but total rubbish at being nice to other people. He caps the entire episode off by waking his mother up to cry about it until she sends him off to go look for a new girlfriend elsewhere.
There are many other stories of Vainamoinen's exploits, including his building of enchanted relics and structures, his awesome musical celebration of the milestones of the other gods, and his eventual exile from the world when he condemns an innocent baby to death and said baby turns out to be the magical fated king of Finland. Like many other creator gods, he's generally benevolent and responsible for a lot of important and useful things existing and being used by mortals and gods alike; but his creations can also be used for irresponsible or evil ends, and he often gets so wrapped up in his projects that he accidentally does things like starting wars or causing disasters without meaning to. Creators always have to live with the idea that their creations can be turned toward malevolent goals, and Vainamoinen is a great example of the fact that the neutral power to make new things cannot control what happens to those things later.
In case you were wondering how to pronounce his name, with all those diaereses and long vowels, here's a sample of a Finnish person pronouncing the name, courtesy of Forvo: