I think it would be interesting to make the death-penalty upgrade have something similar to Oak's Last Stand:
2 / 4 / 6 / 8 seconds (would trigger BEFORE ls).
You would have ZERO hp, and there would need to be some sort of SUPER OBVIOUS way to tell that this ability is active so that an obvious 'fake death' animation such as Oak's Last Stand doesn't become neccassary (and then this upgrade becomes useless). If you are Oak with LS, since you have 0 hp, you die, come right back.
Make it like Zelda fairies: Everyone gets the following buff:
If you fall in battle, you return with 500 hp and 0 mana, and a 5 second +10% movement speed bonus after ??? seconds.
Maybe you would have to increase the revival-hp, maybe you would have to give them half/full mana (Oak shield/Sedna heal/Erebus Mist), maybe you give them an Oak shield for a few seconds (though if it's invincible to stuns then it makes portal-suiciding even easier - I walk up there, try to lock, if I fail, oh well, free shield, teleport out).
Super favor items... not liking them :-/ now SotF is pretty much a neccessity. 1k hp is ... a lot. The 'buff' between BotF (which I considered a strong, high-level favor item but not imbalanced, just really good) and SotF is only 200 hp, sure. That's like 1 auto-attack. But BotF didn't NEED that buff, and it hurts burst-demigods such as TB (the fire auto-attack fixes most of his weaknesses, maybe his Cold Touch could be buffed, and maybe a few other very small +2-5% buffs to other abilities, but a good TB is terrifying).
I think that the other favor items need to be buffed first.
Other options: keep these uber l33t favor items, but make them have drawbacks as well:
Spirit of the Fallen -> Burden of the Fallen
+1100 hp , +8 hps, -200 mana, -3mps
(doesn't affect pure-Ooze UB much but whatever)
+1000 hp, +10 hps, -5% movement speed
Makes Rook even harder to push out of a lane, but even easier to gank if you get the upperhand on him. Not quite as viable for UB, who might need to chase, etc.
+1000 hp, +10 hps, -3% attack speed
-3% attack speed is like 9 dps early game, so not really a big deal. Maybe it needs to be 5%, I don't know.
Haste Anklet ->
... can't think of anything really +2% isn't really game-breaking. I would prefer it to not be Assassin only, but if you compare the superior Assassin-only Staff of Renewel to the universal Diamond Pendant, Staff is clearly the superior and this fits that paradigm.
Maybe you could make it a +20% but it has a small -hps to compensate for it.
Tome of Champions ->
Just made Erebus even more terrifying. The thing about a minion-build Erebus is that he tends to have low hp and isn't very terrifying if you can actually MAKE it to him (many also tend to sacrifice batswarm). Now, he can give up Horn of Battle to give a constant +150 hp bonus to his minions while still retaining a decent amount of hp for himself. Makes hybrids pretty terrifying...