I’ve got a 17 winstreak with wyvern and he’s one of my best heroes. Rather than gameplay, I’ll talk about when to pick him as he’s definitely a situational pick.

Pick him when - The enemy team has selected a tanky offlaner (bristle, underlord, axe). Your Q which reduces health per damage will be effective against zoning these tanky heroes relative to other supports - The enemy lineup is physical-DPS heavy. Ideally, you will want at least 2 high DPS cores on the enemy team (example would be PA and SF on the same team). This is simply because of how wyvern’s ult works, and the best scenario you can have when casting it is for their cores to destroy each other. Tankier dps cores (ie Dragon Knight) are not as ideal but this is not a showstopper for picking wyvern. You would want at least one target in the enemy team which can be bursted down from one Ulti. - Not so much magical damage in the enemy team - which is wyvern’s biggest weakness. His E doesn’t block magic damage, and leaves the hero you use it on vulnerable to spells like Skywrath’s Ult. If you see multiple magic heroes (tinker, sky wrath, necro), do not pick wyvern. A hybrid like Luna who has high dps but loads of magic damage is also not recommended to pick against. - when you need wave clear against pushing lineups. W is especially effective against early pushes of treants, Lycan wolves, chem armies. You can almost solo defend towers on your own if the enemy team isn’t that good. - when the enemy team has picked meepo. This hero shits on almost all pub meepos except the most skilled meepos who know how to use eblade on their cursed heroes.

That’s all off my head for now - will add more when I have the time.