Voadam
Legend
Rereading the Gigantean in the Advanced Bestiary page 136 I was misremembering how big they got. It says "Its size increases by up to four categories over that of the base creature (maximum Colossal; see the following table for new dimensions)."Wouldn't Jotunblood be more appropriate in that case?
I was reading it as choosing one to four sizes so going from large to huge as an option, but re-reading it I see it would go from large to Colossal.
Jotunblood Giant works mechanically to turn a giant one size bigger from large to huge, but the narrative description there is that a jotunblood is a singular bigger giant among other normal sized giants.
Advanced Bestiary page 155:
"Born mightier and larger than usual for their kind, jotunblood giants tower over their fellows both in height and in power. Often called king-giants by the smaller races, jotunblood giants almost invariably live up to that name, acting as leaders of the other giants they live with. Few giant tribes can boast more than one jotunblood giant, and these creatures rarely beget more. Typically, a jotunblood giant is born when a giant tribe lacks strong leadership. Th e birth of a second jotunblood giant to a tribe that already has one is usually seen as a sign from the giant gods that the tribe has grown too large and must split, with the two halves going their separate ways. Reluctance to do so has led to bloody civil wars and long-held grudges."
The Gigantic template from the Deluxe Book of Templates works too by increasing size by any amount, but the template's doubling of base HD for each size increase might be more than is wanted for conversion purposes, or it could be very right (particularly if trying to recreate 4e style higher level titans).