>>718370770
Bring a thunder weapon (Lagiacrus + Thunder res stack is good if no Artian) and see if you can fit Suture jewels in your set. If not, bring Sushifish scales to counter bleeding.
If Seregios is in the Plains you get him the fuck out any location that is enclosed and small. Kick his ass to the open field with a shit ton of thornbushes and stuff every single thornpod down his throat. There's like 20 of them all over the place. It will fuck his shit up real bad. Do not play by his rules and abuse every single environmental advantage you can find. Lure other monsters to keep him distracted. If Rey Dau is in the area he will blow Seregios' brains out.
After he does that large double sweep his leg will always expose a wound for a short topple but this will NOT keep him down long. You can also try to tire him out by not overextending and playing really cowardly/defensively, which then he'll be much slower and less jumpy. Flash him when he's in the air for guaranteed topple. Don't be afraid to spam traps and/or restock items when needed.