Hi guys!
I was immediately thrilled by what you proposed in this thread, evandan, and decided to try it as soon as possible!
So here is my first result at Horde Mode using H=3 (H=2 makes it too easy, I think):
Chrono Ranger and The Eternal Haka managed to kill 48 monsters from the Final Wasteland before falling to their innumerable horde!
I think I could have done much better, but here's what happened:
First, I couldn't manage to draw Haka's Enduring Intercession for a long time, even if I was drawing as many cards as possible with the Haka of Knowledge power. This resulted in Chrono Ranger's premature demise, after only 13 monsters had been defeated. Unfortunately, a few of the monsters targeted the lowest hp target, that is Chrono Ranger, and between Chupacabras and Rat Beasts, he was soon gone.
However, he has been fundamental to the group survival, also killing the Mongolian Death Worm two times! (Once with a Temporal grenade and once through a bounty/tech-strike/compound bow combo.) I just think that his full potential was yet to come.
Then, with Haka alone, and essentially double environment turns (Env > Incapacitated CR > Env > Haka), also counting that I was using both the Ancient Library and Con's Bunker at full potential, there were a lot of monsters for Haka to deal with. I managed to make great use of Rampages, to which I owe at least half of the total 48 kills. The monsters however were slowly chipping at Haka's life, and a couple Abominable Snowmen with a Mongolian Death Worm finally overwhelmed the ageless warrior.
Now some thoughts on this mini-game! I think it's really a great solo game and makes for a fun and thematic experience. Game-wise, Chrono-Ranger is a bit frail to last in a two-player group, and his bounties are a bit harder to use on targets that stay on the board for a rather short time. I think it is hard to use him at full potential, while Haka fares pretty well. All of his cards can be used as effectively as in a regular game (Punish the Weak is still a sub-par damage boost). His Enduring Intercession card goes from useless to priceless, since it essentially allows Haka to tank and keep his one-armed friend alive. Dominion (which I played as Limited card) is also great, and Savage Mana (which I finally decided to play, using counters for keeping track of monsters killed instead of putting the cards under it) provided 8+ damage when needed, allowing him to one-shot Yetis and Worms. As far as the monsters go, they are all pretty vicious, except for one: the Horrid Skunk Ape! Keep this stinky guy around, and he will do more good than bad, damaging the other monsters as well. These monkeys made more than one of Haka's Rampages even more effective, bringing his fellow high hp monsters to 5 hp or less and thus allowing Haka to wipe the board.
So my suggestion is: play it and post some results!