I think that at first as well, until I try to leave one room undefeated to try fighting it after beating the Boss. Turned out I can’t, the game will just consider it finished. So easiest way to earn maximum renown for fraction team and no-dead team in level 500 is to just fight 3 battles (beginning/middle/Boss) to finished the Delve early to minimize casualties.
The problem is, you will always want to beat all rooms in any levels, so how ofen you should try these 2 challenge? Always running them to beat all rooms will be very hard in later levels. So it seems like reaching level 500 in the fastest way using your best team is the main goal, with backtracking those challenges once in a while when you’re stuck without Treasure Hoard’s stat help.
As for the OP, I agree that the synergies could be better. Those extra life gains are great for survival, but not much help in offense strategy. Although it should work well enough in the right team setup.
For Hall of Guardian, an ideal team would be Silent Sentinel/Ethereal Sentry/Gargoyle/Arcane Golem. Skull damage will be the main tactic, with Gargoyle as the main offense spell. Attack stats will be the main source of spell damage with Ethereal Golem’s assistance . Enchanting and multiple damage-reducing traits are great for long survival, with stun to disable those same traits when fighting boss.
For All Seeing Eye, it’s Ocularen Leech/Xerodar/Ocularen/Watch Mother. Their main tactic is stare the enemies down from the top with a mix of skull/spell damage. Top 2 are quite great main offender, with Ocularen to help looping them and take out slacking troops. Watch mother to help with survival, and bring back-up Ocularen Leech in case it died. They are not as bulky as the Guardians, so it’s great to have summoner.