Tetsuo and Invasion of Arcavios // Invocation of the Founders on the battlefield (Invasion of Arcavios // Invocation of the Founders as Invocation of the Founders).
Call to Mind and Said // Done in hand or in your graveyard.
Tetsuo has an Equipment attached to it with mana value 5 or greater.
Tetsuo does not have summoning sickness and cannot be blocked and killed by an opponent.
One of Call to Mind or Said must be in your hand, with the other in your graveyard.
Steps
Declare Tetsuo as an attacker. Tetsuo triggers, causing you to cast Savage Beating without paying its mana cost, choosing its second mode.
Invocation of the Founders triggers, copying Savage Beating.
Resolve both Savage Beatings, causing you to get two additional combat phases after this one.
Move to your first combat phase.
Declare Tetsuo as an attacker. Tetsuo triggers, causing you to cast Call to Mind without paying its mana cost, targeting Said.
Invocation of the Founders triggers, copying Call to Mind, targeting Savage Beating.
Resolve both Call to Minds, causing you to return Said and Savage Beating from your graveyard to your hand.
Move to your second combat phase.
Repeat steps 1 through 4 one additional time.
Declare Tetsuo as an attacker. Tetsuo triggers, causing you to cast Said without paying its mana cost, targeting Call to Mind.
Invocation of the Founders triggers, copying Said, targeting Savage Beating.
Resolve both Saids, causing you to return Call to Mind and Savage Beating from your graveyard to your hand.
Move to your second combat phase, and repeat from step 1.