You must pay the costs to cast that spell
But if you can potentially deal more than 20 damage in just two turns, with a "cashback" if the opponent does try to delete your pumped creature, then the dice usually becomes well worth rolling

A Trail of Teacups Aberrant Researcher Acolyte of Affliction Admiral Brass, Unsinkable Advanced Reconstruction Aftermath Analyst Ainok Wayfarer Airlift Chaplain Altar of the Wretched Angel of Suffering Another Chance Anowon, the Ruin Thief Argoth, Sanctum of Nature Ark of Hunger Armored Skaab Ashcoat of the Shadow Swarm Ashcoat of the Shadow Swarm Atrocious Experiment Autumnal Gloom Avatar Destiny Aven Heartstabber Awaken the Honored Dead Ballad of the Black Flag Bane-Marked Leonin Barrowgoyf Belltower Sphinx Beluna Grandsquall Beluna Grandsquall Billowing Shriekmass Black Widow, Daring Operative Blanchwood Prowler Blight Titan Blood Spatter Analysis Bloodcurdler Blossoming Tortoise Bramble Familiar Bramble Familiar Bristlebud Farmer Bruvac the Grandiloquent Burrowing Razormaw Cache Grab Carrion Cruiser Carrion Grub Cauldron's Gift Cemetery Tampering Cephalid Aristocrat Cephalid Illusionist Cephalid Vandal Chains of Mephistopheles Charmed Pendant Circle of the Land Druid Cloudhoof Kirin Colossal Badger Colossal Badger Colossal Grave-Reaver Combustible Gearhulk Convergence of Dominion Coral Colony Corpse Churn Court of Cunning Covetous Castaway Crawling Infestation Crawling Sensation Crop Sigil Crow of Dark Tidings Daggerfang Duo Dakmor Salvage Darkblast Dawnhand Eulogist Deadbridge Chant Death's Oasis Deathbonnet Sprout

These simple words are meant to evoke plenty of imagery in your mind beyond the card art, and perhaps give you a clue as to what the card does
Gisela, Blade of Goldnight, Ojer Axonil, Deepest Might, and Torbran, Thane of Red Fell unconditionally increase the damage of your burn spells, as do other damage doublers and damage increasers