Hello so I have a question. If I cast Aquitect's will to put a flood counter on an enemy land it gains the “Island” status in addition to its other types. My friend argues that because of this he can tap this land, a swamp for example, now to add both blue and black mana in one turn. I thought it essentially became a dual land that you can use either as a black mana or you could use it as a blue mana. I did not think however that the land was now worth two mana each turn. Any rulings on this as I’m not finding anything. Thanks!
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-MadMage
You are correct, Aquitect's Will doesn't let a player tap a Swamp for UB, but only for U or for B.
If a Swamp becomes an Island due to Aquitect's Will, it will have the abilities "T: Add U" and "T: Add B" (C.R. 305.6, 305.7). Any effect that adds an activated ability with just T in its cost to a permanent that already has one (as in this scenario [C.R. 305.6, 305.7; see also C.R. 205.1b]) doesn't add any effects to the existing ability. For example, if Gruul Turf is affected by Aquitect's Will, its last ability doesn't become "T: Add RG. Add U.", but rather, Gruul Turf now has two separate activated abilities whose costs are each T (see also C.R. 113.2c). And paying the cost of one activated ability doesn't pay the cost for any other, even if it has the same text or the same cost (C.R. 118.10).
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-MadMage
If a Swamp becomes an Island due to Aquitect's Will, it will have the abilities "T: Add U" and "T: Add B" (C.R. 305.6, 305.7). Any effect that adds an activated ability with just T in its cost to a permanent that already has one (as in this scenario [C.R. 305.6, 305.7; see also C.R. 205.1b]) doesn't add any effects to the existing ability. For example, if Gruul Turf is affected by Aquitect's Will, its last ability doesn't become "T: Add RG. Add U.", but rather, Gruul Turf now has two separate activated abilities whose costs are each T (see also C.R. 113.2c). And paying the cost of one activated ability doesn't pay the cost for any other, even if it has the same text or the same cost (C.R. 118.10).
See also this thread and this thread.
EDIT (Jul. 11, 2022): Clarification.