i gotta give you a pdf i used for long time to this topic
its in JP but i'll help you understand the map
http://mectradegroup.com/bcdHydra.pdf
after u read it, this map focus on the top half of dynamidbcd, the hydra section
there indicates 3 big red dots, they are the "key" eye, 1 is the one to pop NMs, other 2 is where the timer will pop, however to pop them there are pre-conditions
the top red dot, which is right after u go upslope from gobbie land, is popped by ONLY AGGROING the 3 redish-purple dots on the top-right side of that mess(focus and you can see those reddish-purple dots w sorry if those color too close)
same for the middle big red dot where the 2nd timer will pop, you will need to ONLY AGGRO the 3 redish-purple dots at the bottom-left side of the mess
thats all tho, but imo, the only one worthy to get is the top right extention since it can be farmed.
however the bottom left mess is way too far to be considered helpful since people usually flee to nue tower nowadays, unless you decide to clr up the mess for it, which prolly take 30-45 mins