When a Mongo baby copies a Demon baby and shoots behind him he will stop doing anything
also, this game is amazing

The Binding of Isaac fangame, heavily inspired by Plants vs. Zombies · By
The biggest problem I have with the game, by far, is the default limit of 4 babies.
Lil Chad, being the equivalent of Sunflower, is a must-pick for normal runs, so that leaves three slots open. I've almost always used Cube of Meat for the second slot, because the defense is very helpful against clumps of enemies, and it hard-counters the worm monster in It's All Mine. That gives me a mere two empty slots, and I have to use at least one of these for an offensive baby. Even then, I've found Brother Bobby to be reliable enough that I keep using him for the earlygame levels.
Thus, the strategy feels stale; there is little room to make creative loadouts with the babies I choose throughout the run. I've learned that choices matter much more for the bosses, because I think they utilize all the babies I've collected. For the regular levels, however, I tend to ignore most of the babies I get, because I constrain myself to a loadout that I think will work for the rest of the run.
Personally, I would set the default limit to 6 babies; that is the amount of seed slots which the original Plants vs Zombies starts the player off with. But I think even 5 babies would seriously open up the game.
I have sanguine bond unlocked in "stuff" but i never encountered it.
Red flies are a pain, but Isaac was never fair (just git good xD)
Is Book of Shadows supposed to last till destroyed? Cause it does.
Is there a way to see health of my babies? Full health pill seems useful only on barricades.
Frosty can attack my front line babies and stuff from off screen without me being able to kill it. It's honestly even more devastating than red flies.
On multiple occasions I ended up pushing a Gurgle off screen with The Bean. Since they don't move forward after they start shooting, once they're off screen they just stay there and it's impossible to kill them without AOE attacks since babies can no longer target them.
I also think the Limited Edition challenge kinda sucks. I got stuck on it for about an hour before I decided to just not bother anymore. You have to get really lucky with enemy spawns to make it out of the early game because its basically a guaranteed game over if they decide to clump together in a single lane or body block each other in adjacent lanes, and as far as I can tell the Stoney near the end is impossible to kill unless he spawns in one of the middle lanes since I could never kill him even if I had as many Wiz Babies placed as I possibly could.
After beating Mega Plum on my second time through the blue room in a single run, something happened where some enemies spawned after all of the enemies were supposed to die. I think this has to do with Mom spawning enemies during the fight, and not only did the enemies remain even during the shop menu, they killed me while I was in the shop, forcing me to restart once I bought my items.