AI targets its own creatures by triggers of Valakut, the Molten Pinnacle

[MorihiroS]

Describe the bug
If a player and his creatures have protection from lands, AI targets its own creatures by triggers of Valakut, the Molten Pinnacle. But there is a word "may" in the text of Valakut, the Molten Pinnacle, which AI ignores.

To Reproduce
Steps to reproduce the behavior:

1. Player has Serra's Emissary with protection from lands
2. AI has Valakut, the Molten Pinnacle, 4+ lands and some creatures
3. AI casts Primeval Titan
4. AI finds 2 lands and targets its creatures by triggers of Valakut, the Molten Pinnacle

Expected behavior
AI shouldn't target its own creatures or itself by triggers of Valakut, the Molten Pinnacle.

Desktop
OS: Windows 10
Java Version: 1.8.0_202-b08
Forge Version: 1.6.60-SNAPSHOT-12.08

Screenshots

[Hanmac]

for the Rules, AI need to target its own creatures, but it should choose not to deal damage to them

You target a permanent or player when the ability triggers. You decide whether to have Valakut deal damage to that permanent or player as the ability resolves.

[Hanmac]

@tool4ever @Agetian we need to look at when the Optional Trigger resolves, if it REALLY still wants to keep resolving

[MorihiroS]

Merged with #4208