Novels like Cardmancer

All share Portal Fantasy / Isekai

Low-Fantasy Occultist Isekai
4.53
Also Dungeon Crawler and GameLit
An Unbound Soul
4.41
Also Reincarnation and LitRPG
Jackal Among Snakes
4.66
Also War and Military and Strategy
Magic Murder Cube Marine (Book 1 Stubbed)
4.69
Also Dungeon Crawler and GameLit
Magic is Programming
4.53
Also High Fantasy and Dungeon Crawler
A (Not So) Simple Fetch Quest
4.63
Also Dungeon Crawler and GameLit
The Gods’ Gacha Game: Return of the God-King (Volume 2 Complete)
4.38
Also Dungeon Crawler and GameLit
A Soldier's Life
4.70
Also Male Lead and Dungeon Crawler
Realms Beneath the Eternal Light Saga
4.47
Also War and Military and Reincarnation
The Value of Zero
4.16
Also Dungeon Crawler and GameLit
Mage Tank
4.57
Also Dungeon Crawler and Reincarnation
Earth's Alpha Prime (a LitRPG System Survival)
3.98
Also Dungeon Crawler and GameLit