Garthanos
Arcadian Knight
Sentinel is still very badassed with that how about you may trade out an extra attack for an extra AoO without expending your reaction this allows more attacks of opportunity but the sentinel is then trading for the benefits of extra AoO (stopping more than one trying to swarm by hurray) ... when it comes up.May seem like a distinction without a difference, but I'd phrase it as taking a certain reaction, like an AoO, "without expending your reaction" once/extra attack you're entitled to - use your reaction for something else, it's gone, and you can't take anymore AoOs, even if you "have some left."
Would tend to keep the lid on things.