I was bored as hell reading about Natural Selection in Biology as I was doing a Lab right before I took my test today and one of the things I saw to show an example was Flies. Flies being immune to poison wouldn't die when exposed to it, and thus would produce more Flies and spread their immunity through their genes.
-------------
This little feature could make insects, besides the Spider, more useful later on. Beetle I don't find terribly much use for, and Fly is useful only early on unless you want a quick Destroy Walls Spell.
--------------
How this works is this:
Randomly an insect creature is generated from the portal. There is a chance, depending on the creature, that one will pop up with a random immunity. These immunities could be possibly immune to gas, immune to freeze, immune to chicken spell, that kinda thing.
If you have, say a Fly, that is immune to Freeze, it will heighten the chances that another Fly will enter your Dungeon with the same immunity. Say one comes in with an immunity to Chicken while you have one immune to Freeze, both spells have a higher chance of getting immune Flies to both. In fact, it is even possible to get one that is immune to both Freeze and Chicken, so now you have a Fly that is immune to Freeze, one who is immune to Chicken, and one that is immune to both... the chances of one to appear with both is quite increased, and the overall chances of a creature having any immunity (Within the two) is now extemely likely.
Spiders have the lowest chance to get an immunity, possibly 20% due to their inablility to change things such as their Fly Diet.
Beetles are extemely adaptable so they have a 65% chance to get an immunity.
Flies are in the middle, with a 40% chance to obtain an immunity.
The Immunities Are:
Freeze
Disease
Slow
Chicken
Gas
Turncoat
Lava (Resistance, cuts damage in half)
These values may seem extemely high, but don't forget that the fact is, you probably won't be getting many insects to begin with. Unless you're trying to "farm" you most likely won't be getting more than a single immunity for each species. 2 if you're lucky, but they probably will be sepperated. To top it off, these aren't especially powerful. There are alot of dangerous spells for the careless keeper to lose their insects to. This is merely a bonus, the effects are long term.
I'm open to suggestions, as long as you aren't trying to pick out the worst possible scenario, aka the RAREST possible scenario, to get rid of this idea just because you personally don't like it, I'd like a good reason.
By the way, this, in the editor, will be one of those checkable things with an input value just so in case you wanted to, you could add it to maybe Horned Reapers.