If an effect requires you to pay some amount of mana to prevent Memory Deluge from being countered, as Syncopate does, that mana wasn't spent to cast Memory Deluge and will not be taken into account
The ability specifically says each opponent, so no players are targeted and it can get around cards that give players hexproof or shroud, like Leyline of Sanctity
The usual flicker targets are still great, like Archaeomancer and Peregrine Drake, but Rassad makes a number of lesser played creatures much more interesting
Alolan Vulpix VSTAR SAR S11a Incandescent Arcana SAR Market ~$150-$300 USD
The first releases lacked uniqueness and were comparatively much more readily available
The strategy here isnt all that complicated, just cast Talrand and make sure your deck is filled with counterspells, bounce spells, and draw spells, and youll win the game pretty quickly with an army of Drake tokens by your side