Ok not even sure this is possible so mayhaps you can let me know what you think. I know it's expensive however an ancient Steg, with the EOTG and ofcourse skink priest. Add to it a skink cheif with the spear and the armys banner, sprinkle in hunachi's blessed totem. Now I know it's a huge point sink but is it legal??
Not possible. The reason is that a character who carries a Battle Standard and uses a Magic Banner CANNOT have other magic items. See bottom of page 93 of Lizardmen. On top of that, having Huanchi's Blessed Totem and the War Spear exceeds the maximum points of magic items a Skink Chief may carry. Lastly, although the Stegadon is treated as a monster with more than one rider, riding a Stegadon is an upgrade that is bought separately for each character. Normally you can not have more than one character riding a monster/mount. I don't mind being flexible with rules so if I were playing against you, I would only allow you to have two riders on a single monster if you payed for both upgrades. Nice try though.