After getting another Heraldic Beast monster, you can discard the added monster via this card's effect to increase its ATK, then use "Advanced Heraldry Art" to Special Summon "Leo" and the discarded monster for a quick Rank 4Xyz Summon– all without using one's Normal Summon.
One could Normal Summon the added Heraldic Beast monster, and perform a second 2-material Rank 4 Xyz summon between it and "Amphisbaena".
If you also have "Heraldic Beast Eale" in your hand (or if you have another Heraldic Beast monster in your hand, you can add "Eale" via "Leo's" effect, instead), you can Special Summon it after Normal Summoning the other Heraldic Beast monster from your hand. Now, you have 3 Heraldic Beast monsters to work with for an even wider variety of summons.
And if you have "Advanced Heraldry Art" in your hands, just Special Summon both Heraldic Beast monsters for a quick Rank 4 Xyz Summon.
A good combo with "Advanced Heraldry Art", is to discard 2 Heraldic Beast monsters with the same Attribute or Type for "Amphisbaena's" Special Summon and its effect, to Xyz Summon a Rank 4 Xyz monster that requires 2 monsters of that Attribute or Type.