Just an idea i came up with at work.i find the lioness/sub male featues a little laking soo...i am aware this would be alot of work but i thing it could improve the game overall
This might be long so I'll cut to the point

1. Injuries.
Males who patrol and lionesses who hunt should have a chance at getting injured. Injuries can be Minor, Serious, can wait until they heal by them self or use a herb bundle( and Possibly Fatal... But that won't mean your lion will die.you'll have time to heal them! If you don't use a herb bundle they will have a low chance of survivor though) Serious injuries could have a chance to give you a scar.

Males: lower skill=higher chance of getting injured

Females: hunting GROUP SIZE and SKILL would define the chance of injury as well as where your lionesses hunt as different prey are defended differently. Injuries also add reason to train more lionesses to hunt
Minor: can still hunt or patrol but increases chances of serious injuries and lowers chance of success takes 1 day to heal
Serious: can not patrol or hunt for 3 days( as it takes 3 days to heal into minor)
---Possibly fatal:THIS WOULD BE RARE!!(maybe a 5-10% chance? Or less?) this one DOES NOT HAVE TO BE INCLUDED IN THIS IDEA but might make this interesting. You have 2 days to heal if you don't you lion will likely die...but if by luck he survives your lion will receive "serious injury" status. You whould get a message to tell you if your lion died or survived

2.Item ideas for injuries:hearb bundles:an SB item,price depends on size. small bundle = 2 uses. Medium= 5 uses. And large= 8 uses how it works: minor injuries are 50% healed by 1 use.serious 25% chance or healing into minor in one use (possibly fatal 10ish% chance of healing into serious)

Stone of protection: SB. (Fairly cheap) 10 "uses" how it works:you assign it to a lion or lioness and it lowers chances of serious injuries by 50%(100% chance of no fatal injuries)for 10 hunts or patrols(only affects assigned lioness during hunts)

And revival: GB item: brings a lion that died before its 10th birthday back to life unless it died of mutation

Map and exploration: perhaps you can send your injured to a shaman to be heal(could offer a set number of healings per day or week...like sharping claws or stud slots) or find healing items in explore(similar to the November event herbs)

Mode switch: a few people said they would like a way to choose between playing a relaxed game(pretty much the way the game is now)and a realistic game(with injuries and lionesses having a chance to die from those suggested injuries) so what if there was a switch on the den page to choose?

Edit: removed invincibility, changed first aid kit to herb bundles clarifide healing times for injury types and rivival use also added shaman idea as suggested by tialura and sikia

Edit 2: shaman offering a set number of free heals and mode switch