A simple little test script I made for testing the (as of this post) unreleased build. 1114 or higher.

Code:
global script live_forever{
    void run(){
        while(true){
            Waitframe();
            if( Link->HP < 1 )Link->HP = 1;
        }
    }
}
..but I died on LV 3. ... XD



Well, that's not so useful is it? So here is a useful item to make: The Ring of Immortality. Not exactly death-proof, sure, but you'll think twice about not searching out those hidden magic containers if you have this little guy!

You could put a sound effect in there too if you like. I got lazy.
Code:
global script slot2{
    void run(){
        while(true){
            Waitframe();
            ring_of_immortality(0);
        }
    }
}


void ring_of_immortality(int sfx)
{

    while( Link->HP < 1 && Link->Item[__inset_item_ID_here__] )
    {
        if( Link->MP > 0 )
        {
            Link->MP--;
            Link->HP++;
        }
        else return;
    }
}
tl;dr version: HP damage consumes magic when Link is HP Critical.