Don't have time now to go deeply into deck and testing it but from paper view, Spark Spark Spark -> 3x Spark. Just do it please
Future fusion, Foolish and Prisma can dump Alius to grave for Hero Blast and then of course its material for Spark. Of course this is for situations when you need it I'm not saying you will dump Alius with Foolish when your half of deck votes for Foolish, but you might get into such situation where your game depends on it. Also Call of the Haunted and Reborn can revive it for Spark if needed.
Then you got Stratos and ROTA which also bring Alius so its a good ratio for 3 Sparks in here. You will raise consistency.
Now you might think what to drop for that Spark and I say drop Tools. Solemn and Warnings drain your LP enough already and see it as this: Debris can clear field easily with Rose then you get tokens mostly and also Miracle Fusion is a move to perform after that storm opened your opponent LP for a direct atk. Then you got Trunade and you got Sparks. This means you can drop Tools, yes it can be needed badly but Spark is high priority here and you got enough clearing tactics to back you up :D
I think thats enough reasons to use 3rd Spark, not to mention speed and draw and advantage it gives you :D
Also for that Prisma if you want a replacement maybe Ocean. Again I'm not totally into your deck and every single move with it but Ocean would be a Hero if you strictly need one to replace Prisma and is a Water for Zero
Also his eff can be useful sometimes (with stratos :D). I'm not sure maybe you can also put something more valuable there instead of him but its just a suggestion.