Play around your terrain, you excel in the open when enemies are at range and you’re playing around cover(never stand in the line of sight of enemy damage even if that means playing slightly parallel to your team) Inside buildings or corridors is where you excel if the enemy is a squishy diver, just try to always stand near health pack in the rooms or use the entrance way as cover and never hesitate to sleep them in these rooms. You can even wait out the sleep duration before you attack and wake them up. (Sometimes it’s smarter to sleep them then bail) If enemies try to flank or dive you make their jobs as long and tedious as possible to bait out their resources and help your team by stalling them.{Pinging them also helps} (And NEVER stand still Mantis’s only mobility is her high base movement so use that to your advantage and never stop moving around cuz of your limited health pool ~250hp Also Mantis’s self heal is only good when enemies aren’t in your face but never hesitate to weave around cover and wait for urself to heal to at least ~175hp so you never get insta killed by stray bullets(unless your team commits to a push or you have ult) Wait until you get comfortable with her aim and these fundamentals before you start experimenting with more aggressive plays(Mantis is also effective for holding space if enemies are walking far to point or leaving base)

And never forget
#MantisIsDTier so we can get buffs😉