I cant get the one card

it's in the temple where you have to use 5 items in each head-statue, that place underwater
disappears and you cant get into it unfortunately

so THAT card is a MUST GET cos you wont get all 27 cards if you
miss it and the flood happens. It shows the actual temple under water if your on the world map, but when you go
under the water the temple disappears

The games designers probably did that on purpose to make you have to play
through the game again if you missed it first time around and didn't get last helper either, for replay value.
AND YES! considering this game and all it's hype.. you'd think there WOULD BE MORE info/wiki on this game but there's
totally SOD ALL! (other than a little Japanese stuff) that's one of the reasons I chose this game to be my FIRST sanctuary.