format is as follows
HINT#combo hold(blah|myhand)^until(blah|mygraveyard)^until(blah|opponentshand)^restriction{type(creature|mybattlefield)~morethan~2}^cast(blah) targeting(blah|mygraveyard)^totalmananneeded({g}{g}{r}{u}{2})
the ai can be told to hold more then one card, until as many condiations as you want are met, until( is a TC and can basically be used in a fasion of saying "hold arbor elf until you have a lord of atlantas in play and a gaint growth in you hand"
once the condiations are met you can later tell it to cast(gaint growth) targeting(arbor elf[fresh]|mybattlefield)...
I also included the whole of the games restrictions system...
so you can get really really creative with this so far.
the next thing I will do is ability targeting and card favoring.