Kog'Maw ADC vs Xerath Support Matchup
Kog'Maw ADC wins 50.5% of 665 Low Elo games against Xerath Support, -0.5 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 Kog'Maw
Use Void Ooze(E) and Living Artillery(R) to clear from range instead of walking into Xerath's poke to contest every minion; Kog'Maw players recommend this when Xerath is pushing and chipping away at his health.
If Xerath spends Q or W and your support lands crowd control, follow with Bio-Arcane Barrage(W) for a short trade; Kog'Maw players advise turning on a poke lane only after its spells are down and your support creates an opening. (Unverified: no source confirms this note.)
Xerath's long-range Q and W can pressure Kog'Maw as he steps up to the wave, while Void Ooze(E) and Living Artillery(R) let Kog'Maw clear from farther back.
Sources
These notes come from r/KogMawMains, checked against the champions' abilities.