I'm afraid to leave this comment because I don't want a nerf, but EMP from Dread level 7 and beyond is really overpowered. It makes any tower except Rotators obsolete, even though Flamers seem to be a better tower, because Rotators don't seem to be affected by EMP. Not sure if this is intended, but it makes the only viable late game tower the Rotator and that doesn't seem too fun even though I love using them. EMP in general does not feel like a fun mechanic since I have the temple upgrade against it, yet there is nothing I can do about it. It really just keeps two other interesting towers from being playable.
Can you please check that the RP investment success rate is accurate? I have failed 6 times in a row with a 50% likelihood of success which is highly improbable and has set me back a few days of progress. Before that last update it was working well, this is just as of update 1.6a
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You must be unlucky, I've tested it, got fair results.