Need help on how to fudge dice properly

Hello, (If anyone from Love Letters to Strahd is reading go away or it'll spoil our camapin)   So I will start by saying i never fudge dice and i never will, i roll my dice openly with my players becasue i like there to be trust and to show just how hard an enemy is hitting. I also expect  the same courtosy with my players. However im pretty new to roll 20 (self issolation and all that)  and need to know how to Fudge a dice roll so it looks normal but it is just rolling very low (nothing over 8) My reasoning for this is that my party is going to be fighting Strahd in his trone room. strahd knows this and im starting to stragise. but initialy he is going to Use Major Illusion to create himself give the Evil Villan monolouge of im gonna kill you and everyone you love (yada yada) and fight the party hoping to blow some spell slots or uses of the Holy Symbol. Im hoping to get 4 rounds of combat and then give them a How Do You Wanna Do This then reveal the illusion.  My issue is that to make it look real strahd needs to roll bad and miss the party with all his attacks or else when he misses on a nat 20 theres gonna be some questions. if i type /r 3+2 it wont show up the same way as /r 1D20+2. is there a way to use some macro for this or are there any other ways around this? if i can get this to work its gonna be a big twitst that i dont think anyone will expect so please any way im all ears.  TL:DR  - I need to fudge my dice to make a strahd illusion more belivable, plz help.  Thanks 

There isn't a way to fudge dice on Roll20.  That would severely undermine the credibility of the platform. There are three things you can do: 1) don't roll openly.  2) roll normally and let the players scratch their heads if something weird happens.  Maybe provide some extra description like "just as Strahd is about to strike you with his long sword, there is a flash of light and he misses..." or "as Strahd's sword fall inexorably toward your, he catches your eye an a look of confusion crosses them as he halts the sword inches from your neck and backs off" 3) use double inline rolls that only show the result [[ [[1d20+8]] ]] or [[ [[8]] ]].

Thanks for the reply. I was worried about this,(although i'm glad that you cant fudge) with some experimenting i reaslied i can type /em Strahd Attacks to hit with a [[1D20-2]] and if i only attack the high AC PCs the illusion might pass for a while. im sure i can find a way to make it work. i think ill chaneg to double incline roles for the rest of the campain though so i dont raise questions

Instead of doing the whole throne room scene, try breaking it up and having it heard echoing through their travels on the final floor before they get to the throne room. During this, have an illusion of him appear at various intersections briefly and have him mock them then move back around the corner and vanish. If you do this cat and mouse teasing, it should really get the player's really worked up.