Doubts on dudley dan

auto (R): [Counterblast (2), choose 1 《Spike Brothers》 from your Hand and send to Soul] When this Unit boosts a Vanguard, you may pay the cost. If paid, search for 1 《Spike Brothers》 from your Deck, call it to a Rear Guard Circle that's without a Unit and shuffle the Deck.

Must we rest the vanguard,dudley dan, who is behind the vg and attack to activate his eff or can we just rest dudley dan first?

Declare Attacker then u declare whether wanna boost or not.

Once boosted, decide whether to trigger dudley dan's effect or not.

Then drive check.

Alright! Thanks!