Things to know in boss rush: Super shellbreaker= Stronger version of shell breaker. Vis virus= Stronger version of stompy. Time cube= strong version of space box. Sun snail= strong version of moon snail. Sun gigasnail= strong version of moon gigasnail. Thats all you need to know :-).
How to reach shrine without gravity power or metal snail: In snail town go to the left bottom side like jimmy said and then hide in your shell while pressing left until you go through the hole, then do the rest like jimmypage21 says to do.
This is way better than the first one XD. The nyan cat song is there to and it's funny to with a troll face. BUT I DON'T LIKE THAT IT WAS ABOUT TO SWEAR!
Glitches:
1. slide through mare carelia where there are blobs and in the middle you sometimes glitch in and enter boss rush.
2. In moon snail/isis' room at the top of the floor(ceiling)(must me on top)(must need high jump)(must have gravity snail) you glitch in sometimes.
3. Escape boss rush from start of it at the top. First collect gravity snail and quickly hold the up arrow while you gravit to the left.
4. Rarely if you are in lux liratra, when you are in the room that has a bunch of wall eyes(the complete black room) at the main right wall(must have devastator) you glitch in and find yourself in mare carelia.
4 glitches=A LOT! Try them out guys, they exist, I will prove it if you try XD.