The Tavern

Uskayaw is an incredibly fun god, I played under them in the experimental build and thought that it was a really cool playstyle and concept, as well as having a really tasteful theme. My problem here is I can't seem to make Uskayaw work for me- I don't know exactly how piety is calculated, what triggers piety gain and what doesn't(do spells? does riposting? does cleaving? etc), what sort of build energizes best with the strategy, and just general strategy. Any help that you people could give me would be vastly appreciated.

I am sure some dev (Lasty probably, as he is author of the god) will come and tell you that you don't need to know exact mechanic to play/enjoy any god, just try different characters and see how they work.

Personally I played the god without knowing mechanic, Mi with axe in heavy armour was getting lots of piety and was killing many paralyzed monsters.

Hit things and kill them. Probably a melee char with possibly axes enjoy that better.
I've been told Uska requires a good amount of invo to be good.

(Edit: removed this bit because apparently my game managed to break in another new and exciting way.)

Invo invest is pretty mild.

Demomspawn make fun usk dudes, vampiric greatsword/battleaxe is the weapon of choice.

All damage done by the player that isn't a cloud or damage-over-time. The value of damage is assessed as a percentage of the damage-receiver's max health, and multiplied by a value based on monster threat level, so that damaging scarier monsters is worth more. Amulet of faith does increase piety gain. Summons don't count as damage by the player for Uskayaw.

You don't need heavy Invo investment, but Invo helps just about every aspect of Uskayaw's powers. I haven't picked a "sweet spot" optimal investment, but you'd probably want to aim for Invo high enough to make use of Grand Finale with some reliability soon after getting 5* piety.

Hitting lots of targets is good, so axes, AOE, and even riposting is good. VM is the best book background for the god, thanks to Toxic Radiance, but AE does all right with Static Discharge and multi-zapping Shock/Lightning Bolt.

Repeatedly going over/under 3* and 4* does not speed up re-use of Solo Time or Pain Bond.

The underlined part surprised me, now I am not sure that damaging scarier monsters is worth more. It looks like killing rats before killing ogre can be more useful as they basically lose 100% HP in one attack unlike Ogre. Or am I wrong?
Basically I mean it all depends on unknown to players formula, if it's linear dependency on max HP and HD then doing 100% max HP damage to HD 1 monster gives more piety than dealing 49% max HP damage to HD 2 monster because 100*1>49*2.

Psst. Get slings + Uska. It's nuts

I've never been sure: what about Tornado?

Great question! I honestly have no idea if tornado's damage is considered to be cloud-based or not.