Acid Golem vs Downred Magician

Can i xyz summon Downred Magician using Acid Golem as xyz material ?

Zac don't give rulings unless you are 100% certain. In this case I'm 100% sure your wrong.

King since Golem stops special summons he will still be active at the point where you would try to summon Downerd. It works the same way it would if you have Vanity's Emptiness on the field.

Yes you could as his effects would be negated. However it would be very dumb to trade a 3000 atk monster under Drain into a 2100 atk monster in that scenario.

thanks for the answer

I just want to expand on the answer given already, so you can use it to answer similar questions yourself in the future, without the help of others.

Before anyone attempts to make an action, the gamestate checks whether or not that action is valid.

The moment you attempt to Special Summon a monster using Acid Golem (or similar cards like Fossil Dyna), the gamestate checks if is valid. Since just before the attempted Summon you are not allowed to Special Summon, you cannot go ahead and Special Summon, even if you want to use 1 of those said monsters, thinking their effects stop the moment you tribute/overlay/remove them from the field in any way for the Special Summon.
It's correct that their effects do not apply anymore when they are removed from the field, but this never happens.

Before you attempt to make some action, the gamestate checks if that action can be made, given the current circumstances (which, in the example given above, it can't). Only then, if the action can be made, will you pay costs and such (tributing/overlaying, etc.).

This is also why you cannot activate effects like that of "Lumina, Lightsworn whatever" if you do not have valid targets in the Graveyard to begin with, eventhough discarding 1 card is a cost for its effect to activate. Why you cannot activate "Mystical Space Typhoon" without there being any Spell/Trap cards on the field to begin with. Why you cannot activate "Rescue Rabbit", "Tour Guide of the Underworld", "Lonefire Blossom", etc. if you do not have a valid monster(s) in your deck to Summon with their effects.