If a permanent has an activated ability with an untap cost and a mana ability with a tap cost, xMage incorrectly allows you to pay the untap cost and then use the mana ability to pay for the rest of the cost

[alexander-novo]

For instance, if [[Mairsil, the Pretender]] has exiled [[Gilded Lotus]] and [[Pili-Pala]], starting from tapped, xMage allows you to activate Pili-Pala's untap ability, and then tap mairsil for Gilded Lotus' ability to pay for the mana cost of pili-pala's ability. But the rules have this to say:

601.2g If the total cost includes a mana payment, the player then has a chance to activate mana abilities (see rule 605, “Mana Abilities”). Mana abilities must be activated before costs are paid.

(emphasis mine)

So once I started paying the costs (untapping with the untap symbol) I should no longer be allowed to activate mana abilities.

[github-actions[bot]]

Mairsil, the Pretender - (Gatherer) (Scryfall) (EDHREC)

{1}{U}{B}{R} Legendary Creature — Human Wizard 4/4 When Mairsil, the Pretender enters the battlefield, you may exile an artifact or creature card from your hand or graveyard and put a cage counter on it. Mairsil, the Pretender has all activated abilities of all cards you own in exile with cage counters on them. You may activate each of those abilities only once each turn.

Gilded Lotus - (Gatherer) (Scryfall) (EDHREC)

{5} Artifact {T}: Add three mana of any one color.

Pili-Pala - (Gatherer) (Scryfall) (EDHREC)

{2} Artifact Creature — Scarecrow 1/1 Flying {2}, {Q}: Add one mana of any color. ({Q} is the untap symbol.)