I got this far by making every combination of the game's boss mechanics that I can think of. This one has the unique trait of always attacking from behind you, so you usually have to attack the vines she makes in front of you, unless you happen to have something that can shoot backwards. She is the first of a set of 7 heart themed monsters that combines the treasure bullets from the shiny battles with various other types of bosses. They are like score bonus rounds that can actually hurt you!
Wow there really wasn't supposed to be this many bosses when I started this "tiny little baby side project," but here we are. I can finally say it has OVER 100 BOSSES, because the latest update also added boss number 101!