Bel'Veth vs Jax Jungle Matchup
Bel'Veth Jungle wins 51.1% of 472 Low Elo games against Jax Jungle, -0.3 points vs expected, 2-patch window 26.19-26.20.
Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.
How to play as Bel'Veth
Keep one Q dash to dodge Jax's Leap Strike and Counter Strike follow-up instead of spending every dash to engage; avoid an isolated duel when Jax has his ultimate active.
When nearby teammates can join, look for a 2v2 or 3v3 instead of taking Jax alone; Bel'Veth players describe those larger skirmishes as her better fight. (Unverified: no source confirms this note.)
Jax can Leap Strike(Q) onto Bel'Veth and follow with Counter Strike(E); Bel'Veth can keep one directional dash from Royal Maelstrom(Q) to dodge that engage.
Sources
These notes come from r/BelVethMains, checked against the champions' abilities.