Cast Splash Portal by paying its mana cost.
Holding priority, cast Dualcaster Mage by paying its mana cost.
When Dualcaster Mage enters, it triggers, copying Splash Portal, with the copy targeting Dualcaster Mage.
Resolve the copy of Splash Portal, blinking Dualcaster Mage.
Repeat from step 3.

Infinite LTB

Infinite ETB

Infinite magecraft triggers

Dualcaster Mage

Splash Portal

Cast Splash Portal by paying its mana cost, blinking Abdel Adrian.
Abdel Adrian leaves the battlefield, returning Archaeomancer and all other cards that were exiled with it to the battlefield.
Abdel Adrian and Archaeomancer trigger.
Resolve the Archaeomancer trigger, returning Splash Portal from your graveyard to your hand.
Holding priority, activate any number of nonland permanents you control by tapping them, adding at least enough mana to cast Splash Portal.
Resolve the Abdel Adrian trigger, exiling Archaeomancer and the mana-producing permanents until Abdel Adrian leaves the battlefield, and creating a 1/1 Soldier creature token for each permanent exiled this way.
Repeat.

Infinite storm count

Infinite creature tokens

Infinite blinking of nonland permanents you control

Abdel Adrian, Gorion's Ward

Archaeomancer

Cast Splash Portal by paying its mana cost, blinking Felidar Guardian.
Felidar Guardian and Preston trigger.
Resolve the Felidar Guardian trigger, blinking another permanent you control.
Resolve the Preston trigger, creating a token copy of Felidar Guardian that is a 0/1 Illusion.
When the Felidar Guardian token enters the battlefield, it triggers, blinking the nontoken Felidar Guardian.
Repeat from step 2.

Infinite landfall triggers

Infinite blinking of permanents you control

Infinite mana lands you control that enter the battlefield untapped can produce

Exile any number of nonland permanents

Preston, the Vanisher

Felidar Guardian

Cast Splash Portal by paying {U}, targeting Pinnacle Monk.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Resolve Splash Portal, blinking Pinnacle Monk.
When Pinnacle Monk enters the battlefield, it triggers, returning Splash Portal to your hand from your graveyard.
Activate the Treasure by tapping and sacrificing it, adding {U}.
Repeat.

Storm-Kiln Artist

Pinnacle Monk // Mystic Peak

Cast Splash Portal by paying its mana cost, blinking Abdel Adrian.
Abdel Adrian leaves and re-enters the battlefield, causing all cards exiled with it to be returned to the battlefield. Abdel Adrian and Repository Skaab's exploit ability trigger.
Resolve the Repository Skaab trigger, exploiting another creature and triggering its second ability.
Holding priority, activate any number of permanents by tapping them, adding at least {U}.
Resolve the Repository Skaab trigger, returning Splash Portal from your graveyard to your hand.
Resolve the Abdel Adrian trigger, exiling the mana producing permanent(s) and Repository Skaab and creating that many 1/1 Soldier creature tokens.
Repeat.

Infinite sacrifice triggers

Infinite death triggers

Infinite mana nonland permanents you control that enter the battlefield untapped can produce

Repository Skaab

Cast Time Warp by paying its mana cost, taking an extra turn.
Cast Splash Portal by paying its mana cost, blinking Scholar of the Ages.
When Scholar of the Ages enters the battlefield, it triggers, returning Time Warp and Splash Portal from your graveyard to your hand.
Repeat each turn.

Infinite turns

Scholar of the Ages

Time Warp

Combos with "Splash Portal"