The Mightstone and Weakstone Combos
Urza, Lord Protector + The Mightstone and Weakstone + Ancestral Statue
Urza, Lord Protector + The Mightstone and Weakstone + Ghostly Flicker
Combo result
Infinite ETB. Infinite LTB. Infinite storm count. Infinite magecraft triggers. Infinite landfall triggers.
Prerequisites
Ghostly Flicker in hand. All permanents on the battlefield. Urza, Lord Protector and The Mightstone and Weakstone melded into Urza, Planeswalker. You control a basic Island.
Urza, Lord Protector + The Mightstone and Weakstone + The Chain Veil
Combo result
Infinite ETB. Infinite LTB. Infinite death triggers. Infinite sacrifice triggers. Infinite activations of loyalty abilities of all other Planeswalkers you control.
Prerequisites
All permanents on the battlefield. Urza, Lord Protector and The Mightstone and Weakstone melded into Urza, Planeswalker.