Stormsplitter and Sorcerer Class on the battlefield.
Sorcerer Class is at least level 2.
({8} magic symbol) at most, depending on how many Stormsplitters and/or other creatures you control without summoning sickness available.
Steps
Activate any creature you control that does not have summoning sickness by tapping it, adding ({R} magic symbol) that can only be spent to cast an instant or sorcery spell, or to gain a Class level.
Repeat step 1 until you control no untapped creatures without summoning sickness, or until you have ({3} magic symbol) ({R} magic symbol) available, whichever comes first.
Cast Seething Anger with buyback by paying ({3} magic symbol) ({R} magic symbol) .
Each Stormsplitter you control triggers, and Sorcerer Class's third ability triggers if it is level 3.
Resolve the Stormsplitter triggers, creating that many token copies of Stormsplitter.
Resolve the Sorcerer Class trigger, if applicable, dealing damage to any target equal to the number of instant and/or sorcery spells you've cast this turn.
Resolve Seething Anger, giving target creature +3/+0 until end of turn, and returning Seething Anger to your hand.
Repeat.
Results
Infinite LTB.
Infinite ETB.
Infinite damage.
Infinite storm count.
Infinite creature tokens with haste.
Infinite magecraft triggers.
Infinitely powerful creatures you control until end of turn.
Infinite blue mana that can only be spent to cast instant and/or sorcery spells.
Infinite red mana that can only be spent to cast instant and/or sorcery spells.