AI finds creatures with 6+ toughness more dangerous than Doran, the Siege Tower

**Describe the bug**
For example, AI finds Catapult Captain more dangerous than Doran, the Siege Tower and tries to kill Catapult Captain, even though Doran, the Siege Tower reinforces Catapult Captain.

**To Reproduce**
Steps to reproduce the behavior:
1. Player casts Doran, the Siege Tower, Giant Ox and Catapult Fodder
2. Catapult Fodder transforms in Catapult Captain
3. AI tries to kill Catapult Captain and Giant Ox

**Expected behavior**
AI should take into account ability of Doran, the Siege Tower and permanents with similar effects when selecting a target to destroy/exile. Destroy Doran, the Siege Tower is more relevant than destroy Catapult Captain or Giant Ox

**Desktop**
OS: Windows 10
Java Version: 1.8.0_202-b08
Forge Version: 1.6.59-SNAPSHOT-11.04

**Screenshots**