Lichenous Lair is too easy. Please make it harder.
Seriously way too easy.
At depth 16, I was able to solo yet another. The only reason I died is that this was the first time I encounters the "super mega hyper combo giant lichen go!" creature -- heck, the first time I've seen lichen combine at all.
After taking it out, and killing the rest of the level, I think I had 15 hearts lying around that I couldn't take with me.
And this is solo, with just a one-star sword and (... Blaster is a two-star gun, right?) Blaster.
Please, do something to make it tougher. Some of the sleeping lichens, or something. But plain yellow ooze on the ground that just wipes up with some sword swings? And so many heart drops?
The deadliest thing on that level is (A) Lag, and (B) Gun puppies appearing out of no where and hitting you while you are lagging :-).

Lichen need more work, generally just more fleshing out.
A fully merged Lichen is still beat by just running towards it when it rushes.
It's the easiest thing to juggle.
They need a more Tortodrone style spike attack, for one.
Their rush attacks need to damage during rush.
The spikes shooting up out of the ground should form an impermeable barrier around the Lichen, but also have a spike attack where they pop out of the ground in a line towards the player, kind of like Azazel from Tekken 6.
And there should be a type of Lichen that eats other monsters.
Hannibal Lichen or something. And they gain control over that monsters powers.
So they might be able to shoot missiles, or teleport like Ash Wolvers. Maybe when they die they explode like Blast Cubes.
They'd also definitely have to change form to reflect what they ate.
Giving Lichen access to Lichen only areas to merge, kind of like little tunnels where they can come together then bust through a wall and mess you up, would definitely increase the risk for players, who would need to stop the lichens from entering in there as well as fight off the ones merging together outside.
Maybe a room with two switches, you come down from the north and there's a switch that opens the gate south of you, but it closes the two gates to the left and right which is where the lichen rush in to merge.
Activating the switch cause Lichen of varying types to spawn in all the rooms and of varying types.
So you can either head south and try to stop them entering the room, or you can stand inside the rooms and blast them as they merge.
Since the only wall the Lichen can bust through is the South facing one, it means that if they close the switch from the other side of the south facing gate, they would still be able to get back up the top once the lichen bust down the wall.
Or all the gates could just open when all the lichen are dead, as a compromise.
Spawning more fully grown lichens, or allowing for certain types of lichen that can create other Lichens would add more of a challenge.
Maybe have some larger types of non-merging lichen degrade into lesser forms upon death.
So a big Sloom explodes, and there are three little Slooms there.
Kind of like the big, lime jelly cubes.
Have tiny rooms with the Oil Lichens and the Blast Cubes in the same place, then have Fire Puppies everywhere.
Pyromaniac's Paradise or something like that.
I think that would be pretty awesome.
There's a lot of things Lichen can do, they're just not really being used or improved in the right ways.
there could be a boss room for a new lichen that just came on my mind:
when everyone enters the room, and presses the party switch, everyone get's knocked back a huge way, and the party switch disappears leaving a round hole, and the floor would be made of something like super strong glass. Then, everyone see a tube in the place of the switch, and 4 other switches appear around in the room, inactive for now. The tube begin to fill with various monsters and most lichens, to form a huge liken mass, that can't get out of the hole, appart from a part of it. The part that stays out would be the boss itself, that the players would need to fight. When the fight oficially begins, an amount of switches equal to the party size, but that don't work while the lichen is out of the hole. The lichen would have ranged and melee attack alike, most in the likes of some other monsters. After receiving some damage, it would loss half of its body, and would be small enough to be trapped in the tube after the palyers hits the switches (if the player take too much time to do so, like, 30 seconds or more, the lichen would regenerate itself with at least half hp, at this part). When closed, fire would be ignited inside the tube, and the lichen would receive damage, but also would break free (3 stage fight >_<), some other mosnters would be tossed in the tube, to feed it, and it would gain some new attack, and act more fiercly every round. After the third and last round, it would bur at all, leaving a empty closed tube, and the drops would appear as if the monster died at the center of the tube door, for everyone to get their deserved reward ^^.
hope you like, and sorry for not organizing it well, i'm in a little rush now.
Some variants of the lichen levels are also a bit short... comparing lichenous lair to the Vanaduke fortress levels, it's almost astonishing how much variation there is in what you get for 10 energy.
That said, one thing that could make this harder would be to increase the likelihood that two lichen will merge. I've taken to blasting away all obstacles, then sitting still for a minute or two in hopes that a giant uber-lichen would form and make the fight more interesting. Otherwise, you're faced with a small army of small, fragile yellow things that can be destroyed with a gun long before they're ever close enough to threaten you.
Alternate suggestions: allow two large lichen to merge; reduce the drop rate for heart containers, more gun puppies or fast enemies (to prevent you from standing still and firing a gun without risk); seed the level with some pre-merged lichens to speed the formation of the uber spikey fellows. (who, incidentally, are still slow and short ranged enough to be taken out with charged gun shots and low risk)