The rescue is trivial nowadays and the process is described on our wiki. It boils down to this:
# mount /dev/YOUR-ROOT-PARTITION /mnt
# artix-chroot /mnt
# mkinitcpio -P
# grub-install --recheck /dev/sda # for BIOS systems
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=grub # for UEFI systems
# grub-mkconfig -o /boot/grub/grub.cfg
# exit
Reboot and profit.