4 attacks for pure druid shambler.
Shamblers are weak as they are. But since it's possible to change dragonform to plantform and you changed Planar Conduit to change depending on if you have epic spell focus conjuration maybe this is possible.
They cant use items, they cant cast spells which means if they get dispelled or breached they cant rebuff in combat, they cant resummon their summons whilst in shape either, they have 50% Bludgeoning Vulnerability making them soft in melee, they have 50% Fire Vulnerability which is one of the most common spell damages ingame and now they can be knocked down in combat.
I know the stats of them are impressive but I have never met anyone being 'scared' of a druid in shapeshift or anyone look at them with anything but pity.
I suggest giving lvl 30 pure druids 4 attacks in shambler form, they cant stack discipline as items wont count in form so they'll have low points for a melee and making the requirement 30 levels druid it would force the discipline to be crossclassed anyways. That would also remove any chance of crossclass trickery or powergaming.