The main advantage of this card is that you could use this card's skill even though you have a grade 0 vanguard, as long as you can pay the cost.
- You could attack with a rear-guard Ancient Dragon, Babyrex in order to activate Squall Rex's skill. Since Babyrex doesn't need Ancient Dragon vanguard to use it's skill, you could sacrifice Babyrex and uses its skill to call Ancient Dragon, Tyrannolegend from your deck to give you two grade 3 rear-guards in early game, ready to attack.
Attack with a reaguard Assault Dragon, Assaultrex then retire it to call this card. You get to draw a card from Assault Rex's effect and get this card's benefit of an extra attack.
- If you do this before attacking with the Vanguard you can pass your trigger effects to Squallrex and if you check a Stand Trigger you can stand the rearguard that boosted Assaultrex and get a full powered column.
After this card used it's effect, retire you have a Savage Mystique to bind it again.