fallout-shelter
I've been playing the Android version for a few days now, and have 33 Dwellers (slow growth FTW?) and I've noticed that I've never been attacked by the Deathclaws that I've heard about.
Do the Deathclaws and other stronger enemies like Raiders with more guns or molerats only show up after a certain number of hours of Vault existence, or perhaps after your Vault reaches a certain number of Dwellers?
It seems that your device isn't supported at all.
Devices with 512 MB of RAM are not supported. This includes the iPhone 4s, iPod Touch Gen 5, iPad 2, iPad Mini Gen 1.
Source: http://help.bethsoft.com/app/answers/detail/a_id/29954
Altough, based on user reviews, it seems to have problems with other devices as well.
I belive your best bet is to hope that there will be an update that will make the game less memory consuming and/or more stable.
Update: A new patch, 1.0.3 came out July 10th. This may help if you have a supported device. I've found the game much more stable after the patch.
According to the in-game guide their health is based upon their level. With out actual numbers and since the dangers seem to scale along with your dwellers though, this is a bit hard to qualify from an end-user standpoint.. but that is what the guide says leveling does.
Research! I had a room with many different levels and I rushed it until I failed to get the following screen shot
This shows the same damage being done to different level players and there is a clear difference over the length of the encounter. So level up those characters! It keeps them alive longer!
Best Answer
Deathclaws start showing up after you have 60 or more Dwellers in your Vault (the tipping point may be 61). They are attracted by Radio signals and the Door opening.