If you want to fusion boost your shop card with the least amount of ability tickets needed, consider checking out the following excellent guide from /u/FuramiT
Hold up! If you are thinking of leveling your 4★/5★ Sicarius card from AL1, consider getting a 3★ Sicarius to AL6 first before augmenting for cheaper overall cost! If you have already augmented your Sicarius above 3★, you can still fuse a 3★ AL6 card into your augmented Sicarius card to transfer all of its ability level!