Playable and enjoyable map. I liked.
Well, let's go to speak of some things:
1) Lava really plays a role as a secondary challenge but could be better applied. How the player will know that lava is about to appear and hurt him? There's no way. Think about it. I suggest you to download Jazz Attack (
http://www.srb2.org/mb/viewtopic.php?t=9123) and play Fire Eye - MAPB4 in CTF. Sit in and look at how lava "gives a clue" when it's about to rise.
Remember, luck is a thing that a player never should depend on, especially in match.
2) I know where the secret room is... (dun!), but this doesn't matter now. I got myself crushed 3 times there. Player needs to spindash to get in there, but if stops spindashing in the passage, he stands up and, once the passage has a low height, got himself crushed. To avoid it, lower the hight to 32FU. This height forces a continuous spindash and the player never will stand up.