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No other class has as much retaliation damage, and damage negation, as the Stone Warden (although Wyrmics run a strong second place). So, at first glance the basic strategy is to maximize Armour, pile on the retaliation (Eldritch Infusion, Shards, and equipment), and take the hits.
Further damage negation comes in the form of Stone Fortress + Resilience of the Dwarves. When these are in effect, you can absorb damage from non-physical (elemental) attacks using your Armour. This is your primary means of survival, and what a potent means it is.
Offensively, your dual-wielded shields don't quite dish out the raw pounding of the warrior classes, but you can summon aid with Elemental Split, or use Deeprock Form to make volcanos and throw boulders.
Mobility is poor. Stone Vines let you close with an entangled opponent via Rockwalk, but they also reduce your regular movement rate by 50%. Adding some movement infusions, or boots of rushing, or similar accessories to help with mobility, would be wise.