If I attack an occupied battlefield with a Galio and have more might, and I also have a Symbol of the Solari on the field, does the showdown result in a tie and all units are recalled?

Yes, if your combat results in both players having units remaining at the battlefield after damage is dealt, it constitutes a tie, and Symbol of the Solari will trigger to recall all units at that battlefield to their controller’s base.

1. The Combat Interaction

• Galio, Indefatigable possesses the text: "I don't deal combat damage."
• In a combat showdown, Rule 460.2.a states the Attacker sums the Might of all their attacking units to determine the damage assigned to the defender's units.
• Because Galio does not deal combat damage, he contributes 0 Might to the Attacker's total assigned damage.

2. Does the Combat End in a Tie?

According to RiftJudge FAQ #5506, a tie occurs when both sides still have units remaining after combat damage is dealt.

• If you have other attacking units: They will deal their damage to the defender's units. If the defender's units are not all destroyed and your own units remain at the battlefield, the combat ends in a tie.
• If Galio is your only attacker: You will deal 0 combat damage. If the defender has any units present, they will remain after the Combat Damage Step, and your Galio will remain. Since both players have units remaining, the combat ends in a tie.

3. Symbol of the Solari Effect

Symbol of the Solari states: "If a combat where you are the attacker ends in a tie, recall ALL units instead."

If the condition for a tie is met:

1. The tie is confirmed after the Combat Damage Step.
2. Symbol of the Solari triggers and places its effect on the chain.
3. When it resolves, all units present at that battlefield are recalled to their controller's base.

Clarification on Recall

Regarding Rule 452:

• Rule 450 defines a Recall as: "A Recall is when a Permanent is relocated from anywhere to its Base without it being a Move."
• Because Symbol of the Solari uses the word "recall," it utilizes the mechanics defined in Rules 449–453, which apply to all Permanents, including units.

Note: I could not fully verify this ruling against the retrieved rules.