Board Thread:General Discussion/@comment-196.53.44.99-20170422142456/@comment-203.214.80.99-20170425061212

The way to force an anomaly onto a target room is to make sure the target is NOT in anagram mode or cursed. Every other room should be CBA or cursed. Then the only room not in that state will take the anomaly when you use the summoner.

Good instructions are in the wiki pages. Search under anomalies or anomaly.