Platform
PC (Windows)
MTG Arena
Steps to Reproduce
Start a match (this occurred during a Premier Draft event).
Control the following untapped creatures:
Agents of S.H.I.E.L.D. (3/6)
Hydraulic Helper (2/3 artifact creature)
Ensure neither creature has summoning sickness or any effects preventing them from becoming tapped.
Attempt to cast Atlantis Attacks using its Teamwork ability.
Try both:
Casting with Auto Tap enabled.
Manually tapping lands before casting.
Expected Result

Arena should allow Atlantis Attacks to be cast using Teamwork, since I controlled untapped creatures with a combined power of 5, satisfying the Teamwork requirement.

After paying the required mana, Arena should prompt me to select creatures to tap for Teamwork.

Actual Result

Arena never allowed Teamwork to be used.

Instead, the client only allowed Atlantis Attacks to be cast by paying its normal mana cost (5UU).

I tested both Auto Tap and manually tapping my lands before casting, but the result was identical. Arena never entered the Teamwork creature selection step.

Additional Information

This occurred during a Premier Draft match and directly affected the outcome of the game.

The attached screenshot was taken during the mana payment step after I attempted to cast Atlantis Attacks. Although the screenshot only shows the normal mana payment interface, I also tested manually tapping my lands before casting, and Teamwork still never became available.

The battlefield contained:

Agents of S.H.I.E.L.D. (3/6) — untapped
Hydraulic Helper (2/3 artifact creature) — untapped

Their combined power was 5, which should satisfy the Teamwork requirement.

Hydraulic Helper was not being tapped to activate its mana ability. I was attempting to tap it only as part of paying the Teamwork cost.

I suspect the interaction may be related to Hydraulic Helper because it has a mana ability with a spending restriction, but I cannot confirm that this is the cause. I can only confirm that Teamwork was unavailable despite the board state appearing to satisfy its requirements.

If this interaction is working as intended, I would appreciate clarification regarding which game rule prevents Hydraulic Helper from being tapped for Teamwork.

Workaround

None found.

Using manual mana payment instead of Auto Tap did not resolve the issue.

Screenshot

Attach the screenshot.