podalecki:

Voldemort was ready. As Harry shouted, “Expelliarmus!“ Voldemort cried,
”Avada Kedavra!”
A jet of green light issued from Voldemorts wand just as a jet of red light blasted from Harry’s – they met in midair – and suddenly Harry’s wand was vibrating as though an electric charge were surging through it; his hand seized up around it; he couldn’t have released it if he’d wanted to – and a narrow beam of light connected the two wands, neither red nor green, but bright, deep gold.