Jayce vs Volibear Top Matchup
Jayce Top wins 52.3% of 962 Low Elo games against Volibear Top, +3.2 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 Jayce
Keep your range, poke when safe, and avoid spending Hammer-form Q to jump onto Volibear; once he is close, use Thundering Blow(E) to disengage and sidestep Sky Splitter(E).
After level 6, keep your health high and avoid letting Volibear push a large wave into your tower; his ultimate can turn the dive into a kill even when you are under turret.
Sky Splitter(E) grants Volibear a shield only if he is inside its blast radius, so Jayce can avoid both its damage and that shield by moving out of the strike area.
How to play as Volibear
Wait until Jayce spends Acceleration Gate(E) before engaging, then use Thundering Smash(Q) to close the gap while his movement-speed tool is unavailable.
Sources
These notes come from r/jaycemains and r/VolibearMains, checked against the champions' abilities.