Spike hurt drifters only on initial fall, but PC gets hit on every walkby - design or a bug?

[Q_Tip]

As per topic. Id wager that rust bulb ticks could have  such immunity, but larger critters are kind of OP this way?

[wildforester]

Drifters can definitely kill themselves on spikes if they’re forced to walk all over them

[Q_Tip]

Hmm, maybe my trap is too shalow, its basically 2 down, with trap doors on top.