You cannot interrupt your rival with an instant, but your rival's spells do not take effect until after you have had a chance to respond with instants and other fast effects
Historic is the Modern and Legacy analog for Magic: The Gathering Arena

Synthoids Abandoned Sarcophagus Abzan Banner Abzan Monument Academy Manufactor Accomplished Automaton Accorder's Shield Acquisition Octopus Adaptive Automaton Adaptive Gemguard Adrestia Adventurer's Airship Adventuring Gear Aegis Automaton Aerial Doombot Aeronaut's Wings Aesthir Glider Aether Spellbomb Aether Syphon Aether Vial Aetherflux Reservoir Aetherjacket Aethersphere Harvester Aetherwing, Golden-Scale Flagship Aetherworks Marvel Aettir and Priwen Agatha's Soul Cauldron Air Response Unit Akroan Horse Akroma's Memorial Alacrian Armory Aladdin's Ring Alchemist's Vial Alhammarret's Archive Aligned Hedron Network All-Fates Scroll Alloy Myr Alpha Myr Altar Golem Altar of Dementia Altar of Shadows Altar of the Brood Altar of the Goyf Altar of the Lost Altar of the Pantheon Amaranthine Wall Ambulatory Edifice Amorphous Axe Amulet of Safekeeping Amulet of Vigor Ancestral Blade Ancestral Carvings Ancestral Katana Ancestral Statue Anchovy & Banana Pizza Ancient Cornucopia Andril, Flame of the West Angel of the Ruins Angel's Feather Angel's Tomb Angelheart Vial Angelic Armaments Angler's Shield Animation Module Annex Sentry Anodet Lurker Antler Skulkin Anvilwrought Raptor Apocalypse Runner Apple of Eden, Isu Relic Arabella, Abandoned Doll

With Nikya, you cant play noncreature spells, but in exchange, your lands tap for double the amount of mana
Black Foil - White Cross Filler Card: Population 2
This is a real feast or famine card that can maintain tempo and board control while youre ahead, but underwhelm when youre playing from behind