If you want to make a d20 (roll) feel less swingy, you can narrow the range of outcomes from that roll.So my gaming group had a mild argument if there was a better alternative than a d20 as one player felt it was very swingy. . .
RuneQuest, Warhammer Fantasy Roleplaying, Age of Sigmar Soulbound, Dragonbane, Fantasy Trip, The One Ring

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.