Cool, gold chest interaction isn't super important, I just wanted to note it as affected by the unit because it is a weird interaction.
One thing I've noticed since starting this thread is that you actually *can* control who gets shielded by lost wanderer. I'm not sure prioritizing unshielded units would help with what I wanted, since I had a front line of a T2 Lost reavers, with a backline of skeleton archers, with the Lost reavers pulling the camp, so before running in I wanted shields on the reavers. Preferably without having to keep the backline out of range of the wanderer.
I totally understand that same group mechanics might not be possible, it was just an idea. It may very well be that grouping mechanics are available only to the interface, and not the units themselves.
The way you can control who lost wanderer shields is via right click. In the forge, spawn a lost wanderer and 4 other units. (4 units to ensure that at max 2 shields there are 2 unshielded units to choose from). Select the lost wanderer (left click), with the lost wanderer selected hover over an unshielded friendly unit, the cursor should change to a '+'. With the cursor a '+' when you right click on the unshielded unit (you cannot apply a shield to a unit that currently has a shield), the sword "slice" of combat sound should play causing the next shield to be applied to that unit.
I'm not sure ways we could make this mechanic more discoverable, but it does actually give you some control over who gets shielded. It seems perhaps weird that this isn't an "active ability", although that would actually make it require an additional 'z' key press, or button. Anyhow, thank you all for the feedback.
Edit: I notice that there is possibly a reason to avoid making this an active ability, currently if you have lost wander + some number of units in a group and you select the entire group, if one of those units does have an active ability you can still select which unit to shield while reserving the 'z' key for activating the ability of the other unit in the group, which is actually pretty convenient.