I've occasionally beaten a scenario in two-handed solo play where, with one deck skirting near the 50 threat limit, I've realized that that deck was probably lost, so the remainder of my play with it was meant only to set up the other deck for the best chance to finish off the quest solo.
I'm sure this has happened to others, so I was curious: has anyone ever explicitly designed a deck to do this? i.e., to help a perhaps slow-starting partner deck to make it through the initial stages of a scenario, without much regard for its own long-term safety. I'm thinking that Tactics Boromir could play a part in such a strategy. Or perhaps just doomed cards with Galadhrim's Greetings exclusively targeted at the other player. Sending Riders of the Mark across the board without ever expecting them back... That sort of thing.
It's *not* that I think that this would be a particularly advisable way to approach any particular scenario -- why not just run a solid deck that DOESN'T threat out in the first three turns? -- but I think it could make for an interesting thematic design.