https://rpg.stackexchange.com/questions/46352/does-a-reach-weapon-allow-you-to-threaten-squares-10-feet-away-or-not

https://www.reddit.com/r/dndnext/comments/ey9vup/please_help_me_understand_why_relentless_avenger/ https://www.reddit.com/r/3d6/comments/e69uqn/how_do_you_use_relentless_avenger_the_lv_7/ https://www.reddit.com/r/dndnext/comments/d1j0uv/question_about_relentless_avenger/

https://tabletopjoab.com/attack-of-opportunity-in-dd-5e-explained/

https://rpg.stackexchange.com/questions/110562/does-the-3rd-benefit-of-the-sentinel-feat-combine-with-reach-weapons https://rpg.stackexchange.com/questions/176664/does-the-reaction-melee-attack-from-the-sentinel-feats-third-benefit-trigger-th

https://rpg.stackexchange.com/questions/116011/is-the-reaction-from-the-third-benefit-of-the-sentinel-feat-considered-an-opport

https://rpg.stackexchange.com/questions/72253/is-a-character-with-the-polearm-master-and-sentinel-feats-unbeatable-in-a-duel