So theres this novel where the mc is reincarnated to the game world and became the commander of the army, and he can summon unit from card (elf, female tanker, and the smart magician etc), last reading he is with enemy commander (female) to defeat the bad guy who going to do stuff white ancient book
I remember he defeated a powerful raid boss, and was transmigrated inside the game before the first installment. It was Legend something...