If udyr solo invades me as Sejuani should i fight him or run?

It depends on multiple factors. How experienced are you opposed to udyr, what is the current itemisation, do you have team support nearby, study the minimap, check your items and his items, try and predict a pattern he might use, what are your and his strengths and weaknesess...After you consider it all and it looks like a bad idea to fight it probably is... Even a strong champion can be beaten if you can outplay him... People think skill is the biggest factor in LOL but it's not, it is a contributing factor but it doesn't decide your ELO or how good you are... The most important thing in LOL is experience... The longer you play the more you get to know about the game, which champion gets the best uses of certain items, jungler patterns, outplay potential of each champion, what to expect from your matchup and how to counter him when behind... Once you learn all this there is no skilled MOBA player that can outplay you without prior experience in LOL...ergo experience matters a lot and the more you play the better you get... Skill is something that comes with practice and everyone can get it with dedication... So should you fight that udyr... What does your experience tell you...

If your team is responding and coming for him? Fight.

Otherwise, I would probably run.

Honestly even if your team is coming you will still prob die and trade 1 for 1 because udyr is a pretty good champ early. I would say run in almost all situations.

No. Bad idea, wait for your team.

Run. Udyr usually wins 1v1s against enemy junglers.

Ping the everloving fuck out of your team to collapse on him.

If it's level 1 and you start W and he doesn't start Q I don't see how you'd lose. I don't remember her W cool down though and I don't know their base stats, so I could be wrong. (Sej W is Flail right?)

depends on runes and masteries if you went scaling and he invades early i'd run. otherwise try to waste his time and get a team mate to assist.

Early if you have the right runes he shouldnt be able to kill you. Just call for team and kick him out of your jungle.

I play a lot of Sejuani. You will lose this fight every time, especially if you haven't hit 6 yet. Even then you will probably lose. The way to play against Sejuani is to make your home in her jungle and either kill her or take everything because she can't do anything early. Somebody like Udyr is a horrible matchup for Sejuani

If your laners can help you, fight. If not, run.

Sejuani loses almost any duel.

I don't play as much Sej now that CinderHulk era is gone but this tip apply to any non duelers against Udyr invading:

If he invades you, it's probably at red/blue at level 2. At red, you should beat that camp from the bushes, so no sneaky play from him. If he comes early, red will be healthy enough, so you can drag the fight and then laners come. Mass ping 'help' if you want assistance.... Otherwise, if udyr shows up at the smite fight, he can just smite and get away easily.

At your blue, it's a bit harder to see coming but don't forget you can always place a ward on the other side of the trees to see him coming. Then depending on camp health or teammates, run/fight/delay.

If you have Nautilus you should definitely fight and stall as your kit can screw him (no one should invade nautilus in solo)