I was wondering how does the Shudderwock works with the overload, cause I'm kinda confused.
I just lost a game when I played Sludge Slurper which does overload me for 1, but after I played Shudderwock it did not overload me (which I needed to win).
Then there are many games when I pick up a spell with overload from Hagatha's Horror and after I play Shudderwock I do get overloaded.
So... I guess the overload is for the card only, not for the battlecry? I know you don't get overloaded when you summon Slurper by the other cards, but you don't get the battlecry either. Or was it some sort of bug?
I couldn't find anything helpful on Shudderwock nor Overload page.
Shudderwock, and cards like Zentimo and Electra Stormsurge, Overload you on every spell. Zentimo can cast three Lightning Bolts, which will charge you with Overload three times. Overload is being charged when the card is played/casted, but in your case, Sludge Slurper isn't actually being played, which is what the Overload is for. It just activates the Battlecry, as read by Shudderwock's own Battlecry.
In short, spells that are cast will give you an extra Overload-cost. Minions with Overload, as rare as they are, will only Overload you when they are played from your hand.