does it need to match the types exactly? Lets say the channeling spell is fire tag, the other spell is fire lighting tags both.
Or, for future references maybe, what about the other way around, channling is multi type, other spell is a single type or multi type with only 1 type tag shared with the channeling spell
The buff it gives is a damage multiplier, so it doesn't care about skill tags, only damage dealt. The buff granted is based on the four damage type tags, so a hypothetical fire/chaos channelled skill would give a buff that grants 10% more Fire damage and 10% more Chaos damage.