This is one of those things which are common enough that I hardly ever give them a second thought but when I do they just stop making sense.
Why are 命中 and 発動 in 使役形? What are the agents (different from subjects) of the verbs 命中 and 発動? Why don't 命中した and 発動する work here? Since 命中させたプレイヤー is the subject of 発動させる, the direct object marked by を is コンボ, what is its indirect object? What/who is made to perform the activation?